Search

Uneven frost heave in roads and railways is a frequent problem in cold regions leading to degradation of structures. To improve drainage, culverts are frequently integrated into road and railway embankments. The presence of culverts changes the temperature distribution in the surrounding soil as cold air passes through the culvert. Consequently, frost depth and corresponding frost heave are increased in the vicinity of the culvert compared to the rest of the structure if frost susceptible soil is present. For an accurate frost related design, information of heat balance between the culvert and the surrounding soil is needed. A field study focusing on convective heat transfer in culverts was conducted in northern Sweden by the authors. Temperatures and air velocities in culverts of three sizes (0.6, 0.8 and 3.4 m) were recorded. Analysis of obtained data is presented in this paper with emphasis on the influence of air velocity on the temperature distribution. Influence of wind on development of airflow in culverts is also addressed. Accuracy of trained gaussian process regression (GPR) models is estimated in predicting temperature distribution inside of culverts. It is concluded, based on the field measurement data, that airflow can significantly affect temperature distribution inside culverts and development of airflow in culverts is largely influenced by the orientation of the culvert in relation to the predominant wind direction. Validerad;2023;Nivå 2;2023-06-02 (hanlid)

In this paper, a new calibration device for an air flow sensor of the VAV terminal unit is designed. Multi-aperture air outlets are designed to meet the calibration requirements of the air flow sensor in a variety of measurement range. The device can calibrate the air flow sensors of different types of VAV terminal unit by a movable flow rectifier without repeating the design of a different calibration pipeline. The Raspberry PI is used to design the high-performance GUI interface and controlling algorithm to achieve a one-button intelligent calibration. The air flow sensors in three different types of VAV terminal units are used to calibrate the experiment. After testing, the differential pressure value measured by the air flow sensor can accurately measure the air flow within the accuracy of 5% after the formula conversion. The conversion from differential pressure values to air flow values requires precise calibration in order to establish an accurate air flow equation, and here the calibration device plays a key role. The negative effect caused by the distance between the flow rectifiers and the VAV terminal unit is discovered. In other words, the distance between the inlet flow rectifier and the air inlet of VAV terminal unit should be kept as close as possible, or within a range of 2~3 cm. Moreover, the distance between the air outlet of VAV terminal unit and the middle-flow rectifier should be kept as close as possible; otherwise, any slight gap will cause a huge error in the calibration result. The research contributes to the further study of airflow sensing technology through the conversion and calibration of differential pressure measurements to accurate air flow values.

The article presents the results of the investigation of the influence of natural and mechanical ventilation in a passenger compartment and in a driver's compartment on the air flow around the bus. The experimental research was carried out in aerodynamic tunnels. Based on the measurements, the air velocities distribution in the boundary layer was determined. Furthermore, the effect of natural ventilation of the interior space on the thickness of the air boundary layer was analysed. The results are presented in the form of distribution diagram and analytical dependencies. The aim of this research was to define the thickness of the boundary layer when the air flows through a vehicle model.

The article presents current research results in the field of airflow through a façade with a width of 1 m and a height of 13.7 m and with a ventilated gap, and its effect on the year-round heat balance of this façade. An idea to influence airflow in the ventilated gap of the façade is presented based on the results of developed software and the suitability of closing the air gap in winter and in the transition period of the year is described. First, the boundary conditions of the calculations, which are further used in the energy balance between the interior of the building and the exterior environment are defined. In order to include these influences, a discrete analytical calculation was created. It consists of the time distribution of the investigated thermal phenomena calculations. A significant finding is an obvious benefit of controlling the airflow through a ventilated gap in the winter and especially in the transitional period of the year. This technological knowledge has a high potential for energy savings related to the heating of buildings. As the calculations show, airflow control through a ventilated façade reduces heat flow by 25–30% on average, and in contrast, it increases heat gains by 20% and the specific values are presented within the article.

Při posuzování nejnižší vnitřní povrchové teploty je dobré přihlédnout i k problematice proudění vzduchu v místnosti, což je zjednodušeně zakotveno ve formě odporu při přestupu tepla. Dané normové hodnoty se mohou ve skutečnosti měnit, a to má vliv na výsledné povrchové teploty. V práci je aplikována hliníková lišta jako vodivý materiál z interiérové strany na kritická místa detailu parapetu dřevěného okna a variován přitom odpor při přestupu tepla. Přesněji je řešena připojovací spára u zasklení k okennímu rámu a dále u rámu ke stěně. Sledujeme přitom chování lišty při různých tvarech a tloušťkách materiálu a hloubce uložení rámu ve stěně a zasklení v rámu. Výsledky ukázaly, jak veliký vliv může odpor při přestupu tepla na interiérové straně mít. When assessing the lowest internal surface temperature, it is good to take into account the issue of air flow in the room, which is simply anchored in the form of resistance to heat transfer. The given standard values may in fact vary, and this affects the resulting surface temperatures. In this work, an aluminum strip is applied as a conductive material from the interior to critical points of detail of the window sill of a wooden window and the resistance to heat transfer varies. More precisely, the connection joint is solved for the glazing to the window frame and further for the frame to the wall. We monitor the behavior of the bar with different shapes and thicknesses of material and the depth of the frame in the wall and glazing in the frame. The results showed how much resistance the heat transfer resistance can have on the interior side.

RESUMO Um defeito típico recorrente nas uniões soldadas, proveniente das condições climáticas como o vento e a umidade, é a presença de porosidades no cordão de solda. E, dependendo da severidade deste fator, poderá provocar a sua falha diante das solicitações mecânicas. Assim sendo, o presente trabalho teve por objetivo analisar quantitativamente a influência das diferentes velocidades de correntes de ar sobre o nível de porosidades em juntas soldadas pelo processo MIG/MAG. Para tanto foi realizado um levantamento da média das velocidades dos ventos na região nordeste e de posse desses dados, foram simuladas tais condições no laboratório durante a soldagem. E por fim, foram realizadas as análises nos cordões solda através de microscopia ótica e a quantificação dos poros para cada uma das condições. Concluiu-se que uma velocidade de correntes de ar no valor de 2,3 m/s proporcionou um nível de porosidade de 3,41 poros/cm², com dimensões médias de 3,96 mm, uma distância média em linha reta entre os poros de 7,97 mm e uma altura média do cordão de 9,0 mm. Já as amostras submetidas à velocidade de correntes de ar de 3,6 m/s apresentaram uma média de poros no valor de 2,31 poros/cm² por amostra, um diâmetro médio de poros igual a 3,57 mm, uma distância média em linha reta entre os poros de 6,40 mm e uma altura média do cordão de 9,77 mm. Estando, as amostras soldadas à 2,3 e 3,6 m/s, em desconformidade com a norma AWS A5.20A5.20M-2005. ABSTRACT A typical recurring defect in welded joints, due to climatic conditions such as wind and humidity, is the presence of porosities in the weld bead. And, depending on the severity of this factor, it may cause it to fail due to mechanical stresses. Therefore, the present work aimed to quantitatively analyze the influence of differ- ent airflow velocities on the level of porosities in joints welded by the MIG / MAG process. For this purpose, a survey of the average wind speeds in the northeastern region was carried out and with these data in hand, such conditions were imposed in the laboratory during welding. Finally, the weld beads were analyzed using optical microscopy and the pore quantification for each of the imposed conditions. It was concluded that an airflow velocity of 2.3 m / s provided a porosity level of 3.41 pores / cm², with average dimensions of 3.96 mm, an average straight line between the pores 7.97 mm and an average cord height of 9.0 mm. The samples sub- mitted to the airflow velocity of 3.6 m / s presented an average pore value of 2.31 pores / cm² per sample, an average pore diameter equal to 3.57 mm, an average distance in straight line between the pores of 6.40 mm and an average color height of 9.77 mm. When the samples are welded at 2.3 and 3.6 m / s, in non-compliance with the AWS A5.20A5.20M-2005 standard.

The AREC team in ME 310 created BUTLER, the User-Centric Smart Home, that serves users to make the home more sustainable, improve resident well-being, and support remote work. Through a network of in-home thermal, electrical, and air quality sensors in conjunction with online weather forecasting and occupancy sensing, BUTLER provides lifestyle integrated suggestions and autonomous control. The user-centric app presents further insight into the energy efficiency of the home on the individual outlet and device level. This report provides the context and motivation for the project and documents the development of the design solution as well as team AREC's prototyping efforts throughout Spring quarter and their final prototype showcased at EXPE 2022.

Метою даного дослідження є попередній розрахунок і моделювання технологічних параметрів процесу висікання картонних розгорток у пневматичній системі засобами автоматизованого проектування SolidWorks. У даний час проектування, модернізація і удосконалення ротаційного обладнання вимагає оригінальних технічних рішень, особливо для виробництва різнопрофільних картонних паковань. Йдеться про якісний технологічний процес висікання в зоні «ніж—контрніж» і взагалі про виконання завершальних робіт. Проблема дослідження стосується ріжучих і обробних виконавчих механізмів. Відповідно використання пневматичних систем може істотно спростити процес висікання. Розроблений на кафедрі модуль для висікання може бути вбудованим у транспортувальну систему. Наприклад, у стрічковий конвеєр. Таке комбінування транспортера і ротаційного модуля для висікання картонних заготовок вимагає додаткових теоретичних і експериментальних досліджень. Equipment for the manufacture of cardboard products is constantly being improved. New sections for die cutting are being designed. As well as devices for carrying out technological processes of die-cutting and cutting down of cardboard products. The tendency to improve the rotational method of trimming and die cutting of sheet materials is increasing. The main problem in the design of die cutting equipment is the quality of the processes performed. The advantages of the rotary die cutting sections include high productivity. Therefore, improving this process is very important. This article deals with the technological process of cutting in the knife-counter—knife zone. The problem of the interaction of cutting actuators is considered. The use of pneumatic systems greatly simplifies the die cutting process. An advantage of the pneumatic die cutting module is that it can be integrated into the transport system. This combination of conveyor and rotary module allows for curved separation of cardboard sweep. The aim of this study is to simulate the technological parameters of the process of cutting cardboard reamers in a pneumatic system. The calculation was carried out by computer aided design. Accordingly, in the working area of die cutting of the pneumatic system, the air pressure changes. Therefore, temperature parameters of air are important parameters. As previous studies have shown, air temperature can affect the performance of the rotary die cutting module. With increasing temperature, the required air flow rate increases to maintain the required working pressure. This is directly related to a decrease in air density with increasing temperature. Improving the geometry of the nozzle of a pneumatic system is an important study. A partial drop in pressure in the working areas of the die cutting can lead to a decrease in the quality of material processing. The basis of the work is research on the influence of air flow and its temperature variables as a characteristic working fluid. Additional studies carried out using the SolidWorks computer-aided design system show the dependence of the air volumetric flow rate on its variable temperature in the working area of the pneumatic rotary die cutting section.

CV Media Smart is a company that involved in the procurement of IT tools in schools and offices. With wide range coverage of schools and companies, CV Media Smart want to add more business process, therefore data center is needed to support existing and added later business process. The focus of this research is on cooling system and air flow. To support this research, NDLC (Network Development Life Cycle) is used as research method. NDLC is a method that depend on development process, like design of business process and infrastructure design. The reason why this research is using NDLC method is because NDLC is method that depend on development process. The standard that used in this research is TIA-942. Result of this research is a design of data center that already meet TIA-942 standard tier 1.

The possibilities of the action of uneven air flows on the grain material in the separating channels are still not used enough. The reason for this is the insufficient knowledge of the processes of interaction of the components of the grain material with an uneven air flow. The purpose of the research is to increase the efficiency of grain material separation according to aerodynamic properties by purposefully changing the diagram of air velocities in the channel sections using the actions of lateral and aerodynamic forces. The separation efficiency of grain material components was determined by trajectory analysis. The different geometry of the pneumatic separation channel was studied. The study of the distribution of air velocity and air pressure vectors in a vertical annular channel was carried out using the FlowVision software. It has been established that a change in the air velocity diagram can be implemented both by changing the geometric parameters of the channel and by additional distributed air supply through the perforation in the side walls of the pneumatic channel. Based on the analysis of the velocity field, an improved scheme of a pneumatic gravitational separator is proposed for separating grain material into three fractions according to aerodynamic characteristics.

Particleboards are widely used in the artificial board market, which can be constructed from a variety of raw materials and require small amounts of energy to be produced. In the particleboard production process, forming machines play an important role as the key equipment for achieving continuous production. In recent years, airflow forming machines have received increasing attention in particleboard production lines because of their strong separation ability and low price. However, the internal flow field is complex and difficult to control, which affects the surface quality and strength of the particleboard. The most pressing technical difficulty is controlling the flow field characteristics of the airflow paver. At present, the research on this subject is conducted primarily through repeated experiments, which entail long research periods and high processing costs. To reduce human and financial costs, in this study, Computational Fluid Dynamics (CFD) is employed to investigate the flow field and the gas-solid two-phase flow field coupled with particle movement of an airflow forming machine. The accuracy of the calculation model is verified by comparing characteristic point velocities obtained from experimental analysis and a simulation. The simulation results show that in practical production, the frequency of a negative pressure fan should be greater than 27 Hz. It is necessary to set the shoulder properly, and the slab smoothness can be improved by moving the shoulder back on the premise of meeting the strength requirements of the box. The distance between the shoulders of the box body should be less than 2570 mm, and particles with uniform diameter should be added to the paving box to reduce the turbulence effect, improve the quality of particle forming and provide actual particleboard production with a solid theoretical foundation.

The paper analyzes the topicality of the research topic, identifies goals, objectives, subject and object of research. The analysis of known studies related to the study of the characteristics of the formation of the air resistance force during the movement of such vehicles as long-haul trains is given. Based on the analysis of the state of knowledge of the issue about the factors influencing the geometric parameters of road trains on aerodynamic drag, the relevance of the study is substantiated, their goal and objectives are formulated. As a result of the analysis of the methods and means of known studies, it was determined that the use of the method of physical modeling would be the most appropriate from the point of view of cost and complexity. An experimental setup has been created, which consists of a fan, an air flow rectifier and a scale model of an articulated train mounted on a special frame, as well as a device for measuring the air resistance force. Analytical studies have shown that the presence of gaps between the elements of the train (semi-trailer and trailer, tractor and trailer) significantly affects the amount of air resistance force, and, consequently, the energy consumption to overcome it. It is shown that the existing methods for calculating the magnitude of the force of air resistance do not take into account these features. The results of experimental studies have confirmed the need to eliminate these gaps. The measures to reduce the force of air resistance of road trains are proposed.

En los flujos de gas a velocidades supersónicas se producen ondas de choque, separación del flujo y turbulencia debido a cambios repentinos de la presión. El comportamiento del flujo compresible se puede estudiar mediante equipos experimentales o por métodos numéricos con códigos de la dinámica de fluidos computacional (DFC). En el presente trabajo, el flujo de aire se simula en un dominio computacional 2D con el código ANSYS-Fluent versión 12.1 para la geometría de una tobera plana, utilizando la ecuación de Navier-Stokes de número de Reynolds promedio (NSRP), con el objetivo de evaluar cinco modelos de turbulencia: SST k−!, k−e estándar, k−! estándar, k−kl−! de transición y RSM. Se obtuvieron resultados numéricos de perfiles de presión estática para las paredes de la tobera y de formas de ondas de choque en el campo de flujo, para dos condiciones de relaciones de presión rp = 2, 008 y rp = 3, 413, los cuales fueron comparados con los datos experimentales del trabajo de Hunter. Se concluye que los resultados numéricos obtenidos con el modelo de turbulencia SST k − ! de Menter (1994) están más ajustados a los datos experimentales de presión estática y de formas de ondas de choque.//In gas flows at supersonic speeds, shock waves, flow separation and turbulence are produced due to sudden changes in pressure. The behavior of the compressible flow can be studied by experimental equipment or by numerical methods with codes of the computational fluid dynamics (CFD). In the present work, the air flow is simulated in a 2D computational domain with the ANSYS-Fluent code version 12.1 for the geometry of a planar nozzle, using the Reynolds averaged Navier-Stokes (RANS) equation, with the objective of evaluating five turbulence models: SST k − !, k − e standard, k − ! standard, k − kl − ! of transition and RSM. Numerical results of static pressure profiles were obtained for the walls of the nozzle and of the shock wave forms in the flow field, for two conditions of pressure ratios rp = 2, 008 and rp = 3, 413, which were compared with the experimental data of Hunter’s work. It is concluded that the numerical results obtained with the turbulence model SST k −! of Menter (1994) are more adjusted to the experimental data of static pressure and shock wave forms.

This paper reports a compact magnetic transducer developed for generating electrical power from respiration. The device incorporates a side-drive turbine rotor with embedded permanent magnets and two stators, integrated into a poly(methyl methacrylate) (PMMA) package for actuation. The novelty and advantage of the design lies in almost full use of the available turbine volume together with two stators for both mechanical and electrical transduction, which leads to high rotational speeds and high voltage generation at low flow rates. A variety of turbine and stator designs were developed. In the best-performing design, the turbine reached 10 krpm rotational speed at 16 lpm flow rate and 74 mbar pressure drop. The open circuit voltage and output electrical power at this speed were measured to be 2.75 V and 0.06 mW on a matched resistive load, respectively. When operated at 10 krpm for 30 s, the device was able to store 1.28 mJ on a 1 mF capacitor. Tests at higher flow rates showed that the turbine can reach 30 krpm, leading to 8.14 V at the stator terminals and 0.51 mW output power. The results demonstrate the feasibility of this device to generate power from respiration, and its potential to be used in portable electronic devices. No sponsor

The multi-nozzle electrospinning is under extensive investigations because it is an easy way to enhance the productivity and also feasible to produce special structure fibers such as core-shell fibers and to fabricate composite fibers of those polymers that cannot form blend solution in common solvent. Control over the multi-nozzle electrospinning fibers deposition has attracted increasing attentions. The most common method was to use the auxiliary electrode. However, the concentrated effect of the works of control multi-nozzle electrospinning deposit was inconspicuous. To enhance the controlling of multi-nozzle electrospinning deposition, a set-up based oppositely charged electrospinning was designed. In this set-up the air flow was used to transport neutralized nanofibers. This electrospinning method was named oppositely charged and air auxiliary electrospinning (OCAAES). The capacity of OCAAES in deposition area and pattern controlling were investigated. By the OCAAES, concentrated and several patterned nanofibers deposition were fabricated. Results showed that nanofiber deposition area and pattern of multi-nozzle electrospinning could be controlled actively, and nanofiber deposition could be fabricated in a quick thickening rate.

The vortices are generated at the conventional transfer channel, having adverse effects on fiber configuration. In a former research, a conventional transfer channel was modified via rounding the transfer channel inlet corner and adding a bypass channel. The simulation results obtained with the modified transfer channel showed that the vortices were eliminated and the inlet air velocity increased. We present the impact of this modification on the yarn properties and fiber straightness. Four groups of yarn samples were spun using the conventional and modified spinning system. Yarn properties and fiber straightness along the rotor groove were evaluated. Results revealed that tenacities of the yarns spun on the modified system, increased in comparison to that of the conventionally spun yarns. The number of nearly straight fibers is increased by 25.55% by using the modified system, which was mainly attributed to the decrease in the number of fibers with trailing and leading hooks.

Pneumatically-actuated soft robots have advantages over traditional rigid robots in many applications. In particular, their flexible bodies and gentle air-powered movements make them more suitable for use around humans and other objects that could be injured or damaged by traditional robots. However, existing systems for controlling soft robots currently require dedicated electromechanical hardware (usually solenoid valves) to maintain the actuation state (expanded or contracted) of each independent actuator. When combined with power, computation, and sensing components, this control hardware adds considerable cost, size, and power demands to the robot, thereby limiting the feasibility of soft robots in many important application areas. In this work, we introduce a pneumatic memory that uses air (not electricity) to set and maintain the states of large numbers of soft robotic actuators without dedicated electromechanical hardware. These pneumatic logic circuits use normally-closed microfluidic valves as transistor-like elements; this enables our circuits to support more complex computational functions than those built from normally-open valves. We demonstrate an eight-bit nonvolatile random-access pneumatic memory (RAM) that can maintain the states of multiple actuators, control both individual actuators and multiple actuators simultaneously using a pneumatic version of time division multiplexing (TDM), and set actuators to any intermediate position using a pneumatic version of analog-to-digital conversion. We perform proof-of-concept experimental testing of our pneumatic RAM by using it to control soft robotic hands playing individual notes, chords, and songs on a piano keyboard. By dramatically reducing the amount of hardware required to control multiple independent actuators in pneumatic soft robots, our pneumatic RAM can accelerate the spread of soft robotic technologies to a wide range of important application areas.

Пищевая и перерабатывающая промышленность России – одна из стратегических отраслей экономики, призванная обеспечивать устойчивое снабжение населения необходимыми качественными продуктами питания. В настоящее время существуют следующие проблемы, сдерживающие развитие хлебопекарной промышленности: физический износ основных производственных фондов; низкая рентабельность производства; зависимость от иностранных поставщиков ввиду недостатка отечественного хлебопекарного оборудования. Проведение модернизации хлебопекарной промышленности позволит расширить ассортимент вырабатываемой продукции, повысить пищевую и биологическую ценность хлебобулочных изделий, снизить удельный расход энергоресурсов на единицу выпускаемой продукции. Равномерность распределения компонентов в смесях на хлебопекарных предприятиях достигается интенсивным смешиванием. Под смешиванием понимают механический процесс, при котором компоненты, первоначально находящиеся раздельно, образуют однородную смесь. Чем равномернее распределены все компоненты, тем более высокая степень однородности смеси. В статье предлагается модернизированный мукосмеситель, исключающий возвратом муки на эту же машину для повторного смешивания, а также интенсифицирующий процесс приготовления муки и улучшающий качество готовой продукции., The food and processing industry in Russia is one of the strategic sectors of the economy, designed to ensure a sustainable supply of the population with the necessary high-quality food. At present, there are the following problems that hinder the development of the bakery industry: physical wear and tear of fixed assets; low profitability of production; dependence on foreign suppliers due to the lack of domestic bakery equipment. Modernization of the bakery industry will allow expanding the range of manufactured products, increasing the nutritional and biological value of bakery products, and reducing the specific consumption of energy resources per unit of manufactured products. The uniform distribution of the components in the mixtures in the bakery is achieved by intensive mixing. By mixing is meant a mechanical process in which the components, initially separate, form a homogeneous mixture. The more evenly all components are distributed, the higher the degree of homogeneity of the mixture. The article proposes a modernized flour mixer, which excludes the return of flour to the same machine for re-mixing, as well as intensifying the flour preparation process and improving the quality of the finished product.

Since May 2020, several COVID-19 outbreaks have occurred in the German meat industry despite various protective measures, and temperature and ventilation conditions were considered as possible high-risk factors. This cross-sectional study examined meat and poultry plants to examine possible risk factors. Companies completed a self-administered questionnaire on the work environment and protective measures taken to prevent SARS-CoV-2 infection. Multivariable logistic regression analysis adjusted for the possibility to distance at least 1.5 meters, break rules, and employment status was performed to identify risk factors associated with COVID-19 cases. Twenty-two meat and poultry plants with 19,072 employees participated. The prevalence of COVID-19 in the seven plants with more than 10 cases was 12.1% and was highest in the deboning and meat cutting area with 16.1%. A subsample analysis where information on maximal ventilation rate per employee was available revealed an effect for ventilation rate (adjusted odds ratio (AOR) 0.996, 95% CI 0.993-0.999). When including temperature as an interaction term in the working area, the effect of the ventilation rate did not change. Increasing room temperatures resulted in a lower chance of obtaining a positive COVID-19 test result (AOR 0.90 95% CI 0.82-0.99), and a 0.1% greater chance of a positive COVID-19 test for the interaction term (AOR 1.001, 95% CI 1.000-1.003). Our results further indicate that climate conditions and low outdoor air flow are factors that can promote the spread of SARS-CoV-2 aerosols. A possible requirement for pandemic mitigation strategies in industrial workplace settings is to increase the ventilation rate., 28 pages, 0 figures

Vaporized cannabis is believed to be safer than smoking, but when heated to excessive temperatures nearing combustion (>900 °C) harmful byproducts may form. While some cannabis extract vaporizers operate well below these high temperatures, heating coil temperatures obtained during actual use are frequently not reported and many operate at high temperatures. We report on two major objectives: 1) development of an infrared thermography method to measure heating coil temperatures in cannabis extract vaporizers during a simulated puff and 2) a comparison of temperature- to voltage- controlled cannabis extract vaporization systems during a puff. Infrared thermography was used to measure heating coil temperatures in one temperature-controlled and two voltage-controlled systems. The cartridges were modified for direct line-of-sight on the heating coils, the wick and coils were saturated with cannabis extract, and fixtures were developed to force two liters per minute air flow past the coils for the full duration of the puff allowed by the device. The voltage-controlled systems produced higher temperatures with greater variability than the temperature-controlled system. At the highest temperature setting (420 °C) the temperature-controlled system reached an average heating coil temperature of 420 ± 9.5 °C whereas the 4.0V setting on the variable voltage system reached an average temperature of 543 ± 95.9 °C and the single voltage (3.2V) system an average of 450 ± 60.8 °C. The average temperature at the lowest setting (270 °C) on the temperature-controlled system was 246 ± 5.1 °C and the variable voltage system (2.4V) was 443 ± 56.1 °C. Voltage alone was a poor indicator of coil temperature and only the temperature-controlled system consistently maintained temperatures less than 400 °C for the full puff duration. These lower temperatures could reduce the likelihood of harmful thermal degradation products and thus may reduce potential health risk to consumers when vaporizing cannabis extracts.

Larvae of Hermetia illucens, also commonly known as black soldier fly (BSF) have gained significant importance in the feed industry, primarily used as feed for aquaculture and other livestock farming. Mathematical models such as the Von Bertalanffy growth model and dynamic energy budget models are available for modelling the growth of various organisms but have their demerits for their application to the growth and development of BSF. Also, such dynamic models were not yet applied to the growth of the BSF larvae despite models proven to be useful for automation of industrial production process (e.g. feeding, heating/cooling, ventilation, harvesting, etc.). This work primarily focuses on developing a model based on the principles of the afore mentioned models from literature that can provide accurate mathematical description of the dry mass changes throughout the life cycle and the transition of development phases of the larvae. To further improve the accuracy of these models, various factors affecting the growth and development such as temperature, feed quality, feeding rate, moisture content in feed, and airflow rate are developed and integrated into the dynamic growth model. An extensive set of data was aggregated from various literature and used for the model development, parameter estimation and validation. Models describing the environmental factors were individually validated based on the data sets collected. In addition, the dynamic growth model was also validated for dry mass evolution and development stage transition of larvae reared on different substrate feeding rates. The developed models with the estimated parameters performed well, highlighting their potential application in decision-support systems and automation for large scale production.

The paper describes the development of a mathematical model for the motion of a seed mixture particle in the aspiration channel of the separator after the particle passes the cone-shaped spreader and enters the workspace of the aspiration channel in the pneumatic dynamics and vibration unit devised by the authors. The unique feature of the proposed new design is the presence of the central pipe with sail members in the aspiration channel. The sail members in the air stream generate the self-oscillatory mode of motion of the central pipe, which results in the efficient separation of the grain seed mixture into the required fractions. On the basis of the prepared equivalent schematic model, the differential equations of the motion of a seed mixture particle in the process of aspiration separation have been generated. Basing on the results of the PC-assisted numerical modelling of the motion paths, on which the material particles (seeds) of the heavy and medium fractions travel, it has been established that they move on different courses, and the course of the heavy fraction seeds is such that, after they pass the cone-shaped spreader and advance further in the air stream through the space of the aspiration channel, they move closer to the pipe of the aspiration channel. Also, their velocities and accelerations are greater than the same kinematic parameters of the medium fraction seeds. The seeds of the light fraction move upwards under the action of the air stream and leave the aspiration separator at its top.

Введение: рассмотрено значение качественной сушки перед нанесением антикоррозионных составов в процессе консервации и постановки на хранение сельскохозяйственной техники, а такжепредставлены отдельные устройства для очистки и подогрева воздуха, используемые в различных отраслях промышленности. Предложены технические пути усовершенствования существующих установок для сушки сельскохозяйственной техники. Материалы и методы: представлена экспериментальное устройство, отличительной особенностью которого является рекуперация теплоты посредством входящей в конструкцию приточно-вытяжной установки, а также использование подогретого воздуха для сушки как сельскохозяйственной, так и автотранспортной техники. Результаты: теоретические исследования показывают, что энергоэффективность процесса сушки можно значительно повысить за счет использования специальной сменной насадки, обеспечивающей концентрацию воздушного потока в локальной зоне, а также контроль её приближения к поверхности объекта сушки. Обсуждение: выявлена необходимость в обосновании процесса испарения влаги с поверхности машин, при котором не должны изменяться физико-химические свойства насадки экспериментальной установки для ускоренной сушки сельскохозяйственной техники. Анализ теоретических зависимостей показал, что скорость сушки прямо пропорционально зависит от скорости воздушного потока и его температуры. Заключение: предлагаемое устройство по сравнению с другими техническими средствами обладает рядом существенных преимуществ, однако в настоящее время не определены зависимости режимов сушки в зависимости от степени приближения насадки до объекта, что будет являться дальнейшим продолжением данной работы., Introduction: the importance of high-quality drying before applying anti-corrosion compounds in the process of conservation and storage of agricultural equipment is considered, as well as individual devices for cleaning and heating air used in various industries are presented. Technical ways of improving existing installations for drying agricultural ma-chinery are proposed. Materials and methods: the experimental plant is presented. Its distinctive feature is the recovery of heat by means of the supply and exhaust unit included in the design, as well as the use of heated air for drying both agricultural and motor vehicles. Results: theoretical studies show that the energy efficiency of the drying process can be significantly improved through the use of a special replaceable nozzle, which ensures the concentration of air flow in the local zone, as well as control of its proximity to the surface of the drying object. Discussions: the need to justify the process of evaporation of moisture from the surface of machines, in which the physicochemical properties of the nozzle of the experimental setup for accelerated drying of agricultural machinery is identified, is revealed. The analysis of theoretical dependences showed that the drying speed is directly proportional to the speed of the air flow and its temperature. Conclusions: the proposed installation in comparison with other technical means has a number of significant advantages, however, at present, the dependences of the drying regimes are not determined depending on the degree of approach of the nozzle to the object, which will be a further continuation of this work.

The practice of separating grain mixtures with the use of the difference in the aerodynamic properties of their components has proved that the process of separating mixtures in the aspiration separator is the most promising one with regard to the improvement of quality and intensification of production. The authors have developed a new improved design of aspiration seed separators, in which the work process of separating seed material is performed with the use of vibration processes. In this seed material separator, the constant force air flow that acts on the sail members on the central pipe of the separator, when seeds are fed for processing, generates self-excited oscillations in the pipe, which produces centrifugal forces of inertia in the seed feeding system. As a result of the mentioned effect, the propelling force in the process under study substantially increases, accelerating the seeds of different fractions, which differ in their masses, to different velocities. The motion paths of the seed particles change accordingly, heavier particles moving closer to the vertical axis of the aspiration channel, which provides for increasing the efficiency of separation of the seeds of different fractions from each other. In this paper, a new mathematical model is developed for the motion of a seed mixture material particle in the operating space of the separator’s aspiration channel. The mathematical modelling of the process of vibration and aspiration separation has indicated that the separation of the motion paths of the medium and heavy fractions takes place within the range of 20–40 mm; the flying speed of the particles is equal to 3.2–8.0 m s–1, respectively; and their acceleration is equal to 1.8– 3.3 m s–2, which provides the necessary conditions for the accurate and high quality separation into the required fractions. In view of the found differences between the kinematic characteristics of the separated fractions of the grain mixture, the diameter of the pipeline for the medium fraction is to be within the range of 90–100 mm, for the heavy fraction – 50–70 mm.

Стаття присвячена визначенню ступеня травматизації слизової оболонки носової порожнини з турбулентним повітряним потоком. Прохід повітря через верхній носовий хід забезпечує доставку молекул одоривертора в чутливі області нюхового аналізатора. Вивчення характеристик повітряного потоку в верхньому носовому проході дозволяє визначити межі пристінкового ламінарного повітряного підслою та вивчити назальну аеродинаміку на мікрорівні. Турбулентний потік сприяє надмірному висушуванню слизової оболонки носової порожнини, що призводить до її морфологічної перебудови до субтрофного процесу. Було виявлено, що товщина ламінарного підслою становить близько 1 мм, тому прошарок слизової оболонки піддається сушці із збільшенням турбулентності течії в місцях звуження носової порожнини (нюхової щілини)., The aim of the work is to determine the degree of traumatization of the mucous membrane of the nasal cavity by turbulent air flow. It should be noted that it is especially important to determine in the narrowing of the nasal cavity (olfactory gap), where the mucous membrane is subjected to drying with increasing turbulence of the air flow. Achieving this goal will increase the effectiveness of diagnosis and treatment of respiratory and olfactory disorders and will help to identify the pathogenesis of chronic rinological diseases. An important characteristic of nasal breathing is the distribution of air flow rates along the sections of the nasal cavity. When analyzing the existing approaches, it was determined that the main method of studying the aerodynamics of the nasal cavity is rhinomanometry. However, there is not always a clear correlation between anatomical and functional indicators, as well as subjective feelings of the patient and rhinomanometric data. The passage of air through the upper nasal passage ensures the delivery of odorivector molecules to sensitive areas of the olfactory analyzer. The study of the characteristics of the air flow in the upper nasal passage allows us to determine the boundaries of the near-wall laminar air sublayer and to study nasal aerodynamics at the micro level. Turbulent flow contributes to the excessive drying of the mucous membrane of the nasal cavity, leading to its morphological rearrangement towards the subatrophic process. It was found out that the thickness of the laminar layer is of the order of 1 mm, therefore the protuberances of the mucosa are subjected to drying with increasing turbulence of the flow at the sites of narrowing of the nasal cavity (olfactory gap). The prospect of work is the study of the characteristics of the boundary layer in typical pathologies in various respiratory regimes, which will improve the efficiency of diagnosis and treatment of respiratory and olfactory disorders and will help to identify the pathogenesis of chronic rinological diseases., Статья посвящена определению степени травматизации слизистой оболочки носовой полости с турбулентным воздушным потоком. Прохождение воздуха через верхний носовой ход обеспечивает доставку молекул одоривертора в чувствительные области обонятельного анализатора. Изучение характеристик воздушного потока в верхнем носовом проходе позволяет определить границы пристеночного ламинарного воздушного подслоя и изучить назальную аэродинамику на микроуровне. Турбулентный поток способствует чрезмерному высушиванию слизистой оболочки носовой полости, что приводит к ее морфологической перестройке к субатрофическому процессу. Было обнаружено, что толщина ламинарного подслоя составляет около 1 мм, поэтому участок слизистой оболочки подвергается сушке с увеличением турбулентности течения в местах сужения носовой полости (обонятельной щели).

The article presents an improved experimental-theoretical method for calculating the particle trajectory in a pneumatic separating channel. Mathematic simulation of the velocity field of the air flow in the longitudinal-vertical plane of the pneumatic separating channel is made on the basis of measuring their actual magnitude and direction at the nominal grain load. Calculation and construction of particle trajectories is performed with regard to their ricochet from the channel walls. The improved method includes three stages. At the first stage, the vector field of airflow velocity in equal rectangular centers located in the separation area throughout the height and depth of the pneumatic separating channel are determined experimentally. At the second stage, on the basis of particular values of velocity vectors in the rectangular centers the systems of math equations are made. They describe the vertical and horizontal components of these velocities in the corresponding sectors of coordinate axes. At the third stage, the system of differential equations of particle motion in a pneumatic separating channel relative to a Cartesian coordinate system is made and their trajectories are calculated. This improved method raises the accuracy of calculation the particle trajectory inside the pneumatic separating channel and aerodynamic parameters of particles when leaving it. It results in speeding up the process of optimization of the design parameters of the channel and the attached elements of the pneumatic system.

Professional oral hygiene is fundamental to prevent peri-implant disease. Appropriate instruments should be used in patients with restorations supported by dental implants: they should be effective in deposits removal without damaging the implant components surface. The aim of the present study is to investigate and summarize the results regarding the efficacy of oral hygiene techniques described in the literature in the last 10 years in patients rehabilitated with dental implants not affected by perimplantitis. The present systematic review was conducted according to guidelines reported in the indications of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA). The focused question was: “Which are the most effective instruments for professional oral hygiene on implants not affected by perimplantitis?”. The initial database search yielded a total of 934 entries found in PubMed®/MEDLINE and Cochrane Library. After full text review and application of the eligibility criteria, the final selection consisted of 19 articles. The risk of bias of included studies was assessed using the Newcastle Ottawa scale (NOS) and the Cochrane Handbook for Systematic Reviews of Interventions. Curette, scalers and air polishing were the devices most frequently investigated in the included studies. In particular, glycine powder air polishing appeared to be significantly effective in reducing peri-implant inflammation and plaque around implants. The application of the more recent erythritol powder air polishing also yielded good clinical outcomes. Further studies are needed to improve the knowledge on the topic in order to develop standardized protocols and understand the specific indications for different types of implant-supported rehabilitations.

Monitoring of fecal indicator bacteria at recreational waters is an important public health measure to minimize water-borne disease, however traditional culture methods for quantifying bacteria can take 18–24 hours to obtain a result. To support real-time notifications of water quality, models using environmental variables have been created to predict indicator bacteria levels on the day of sampling. We conducted a systematic review of predictive models of fecal indicator bacteria at freshwater recreational sites in temperate climates to identify and describe the existing approaches, trends, and their performance to inform beach water management policies. We conducted a comprehensive search strategy, including five databases and grey literature, screened abstracts for relevance, and extracted data using structured forms. Data were descriptively summarized. A total of 53 relevant studies were identified. Most studies (n = 44, 83%) were conducted in the United States and evaluated water quality usingE.colias fecal indicator bacteria (n = 46, 87%). Studies were primarily conducted in lakes (n = 40, 75%) compared to rivers (n = 13, 25%). The most commonly reported predictive model-building method was multiple linear regression (n = 37, 70%). Frequently used predictors in best-fitting models included rainfall (n = 39, 74%), turbidity (n = 31, 58%), wave height (n = 24, 45%), and wind speed and direction (n = 25, 47%, and n = 23, 43%, respectively). Of the 19 (36%) studies that measured accuracy, predictive models averaged an 81.0% accuracy, and all but one were more accurate than traditional methods. Limitations identifed by risk-of-bias assessment included not validating models (n = 21, 40%), limited reporting of whether modelling assumptions were met (n = 40, 75%), and lack of reporting on handling of missing data (n = 37, 70%). Additional research is warranted on the utility and accuracy of more advanced predictive modelling methods, such as Bayesian networks and artificial neural networks, which were investigated in comparatively fewer studies and creating risk of bias tools for non-medical predictive modelling.

In this study, a series of small-scale experiments were conducted to investigate the backdraft phenomenon in a compartment (1.1 × 0.4 × 0.75 m) with woodblocks as fuel. This research focused on the effects of compartment window woodblock areas on backdraft time, with a video recording of the experimental phenomena. Thermocouples and a gas analyzer were used to measure the temperature and the concentration of gas components in the compartment, respectively. There was no additional heat source or ignition source pre-set in the compartment at the beginning of the experiments; the experimental processes only depended on the heat released from the burning or smoldering of woodblocks. When compartment ventilation improved, smoldering of woodblocks became intense, and backdraft occurred. The results show that backdraft time is shorten with increases of compartment window and woodblock areas, and opening the upper window of a compartment could avoid the backdraft phenomenon. The results help to understand the backdraft phenomenon of solid fuel and, more importantly, could help firefighters adopt reasonable fire-fighting strategies for restraining backdraft occurrence.

Solar drying using greenhouse dryers is a viable method from the technical, economic, and environmental perspectives, allowing the drying of agricultural products for conservation purposes in different regions of the world. In Colombia, the drying of aromatic plants such as mint (Mentha spicata) is usually done directly and in open fields, which exposes the product to contamination and loss of quality. Therefore, the objective of this research was to use a three-dimensional computational fluid dynamics (CFD-3D) model previously successfully validated and implemented in this work to study the performance of air flow patterns, temperature, and humidity inside four greenhouse-type dryers contemplated for a region with hot and humid climatic conditions. The results found allowed us to observe that the spatial distribution of temperature and relative humidity are related to the air flows generated inside each dryer, therefore, there were differences of up to 7.91 °C and 23.81% for the same evaluated scenario. The study also allowed us to conclude that the CFD methodology is an agile and precise tool that allows us to evaluate prototypes that have not been built to real scale, which allows us to generate useful information for decision-making regarding the best prototype to build under a specific climate condition.

Background. Computational fluid dynamics (CFD), a rapidly developing instrument with a number of practical applications, allows calculation and visualization of the changing parameters of airflow in the upper respiratory tract. Objectives. The aim of this study was to demonstrate the advantages of CFD as an instrument for noninvasive tests of the larynx in patients who had undergone surgical treatment due to bilateral vocal fold paralysis. Material and Methods. Surface measurements of the glottic space were made during maximum adduction of the vocal folds. Additionally, the following spirometric parameters were determined: forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and peak expiratory flow (PEF) rate. Based on the measurements, commercial mesh generation software was used to develop a geometrical model of the glottic space. The computations were carried out using a general purpose CFD code. The analysis included patients who were surgically treated for BVFP in the authors’ department between 1999 and 2012. The study group consisted of 22 women (91.67%) and 2 men (8.33%). Results. It was observed that the pressure drop calculated for free breathing depends on the area of the glottis and is independent of its shape. Importantly, for areas below approx. 40 mm2, a sudden rise occurred in the resistance to flow; for the smallest glottic areas studied, the pressure drop was almost 6 times higher than for an area of 40 mm2. Consequently, in cases of areas below 40 mm2 even minor enlargement of the glottic opening can lead to a marked improvement in breathing comfort. Conclusion. Computational fluid dynamics is a useful method for calculating and visualizing the changing parameters of airflow in the upper respiratory tract.

The interest in applying the solar chimney systems for either simple ventilation or electrical energy production is recently growing and thus determination of its behavior becomes essential for its proper designing and sizing. The goal of the paper was to simplify the designing process for mass and energy flow through solar collector – chimney system. The analyzed model consists of a collector made from two flat horizontal discs between which the air runs axisymmetrically to the center. In the middle of the disc collector a vertical cylindrical heat-insulated chimney is mounted. The upper disc of the collector is subject to the thermal radiation. The airflow through the solar collector system and a chimney, is described by stationary equations of conservation momentum (Navier-Stokes equation), mass and energy, which are solved analytically under the boundary conditions: zero velocity of the air speed on the inner surfaces of the disks of the collector and the chimney. On the outer surface of the disc collector assumes a steady stream of heat radiation, which is an analyzed parameter. It assumes the constant temperature and the constant pressure of the air on inlet to the collector. An incompressible, viscous and axisymmetric flow of Newtonian fluid was analyzed in the collector gap. The air flow in the chimney is regarded as a movement in an insulated externally cylindrical vertical tube, which is caused by the buoyant force resulting from the density difference between the heated air relative to the outside air. Theoretical analysis allowed to get involved system of three nonlinear analytical equations in dimensionless forms that have been saved. Dimensionless numbers for the problem are well known in the literature on fluid mechanics and thermodynamics:: Reynolds, Grashof, Galileo, Biot and Prandtl. In the analyzed equations are also dimensionless geometric parameters expressing the ratios of basic geometrical dimensions of the collector system-chimney: the radius disc collector to the thickness gap, the height and radius of the chimney. In the system of equations, the Reynolds number is treated as the determined number, which is a novelty of the method used. The calculation approach presented in the paper allows for significant simplifying the designing process for mass and energy flow through solar – chimney system.

The continuous growth of ore train lengths demands more efficient schedules, improved transit estimations and accident prevention schemes. Braking is a key component in achieving these objectives. Understandably, physical testing is potentially dangerous and costly. Meanwhile, the computational cost of calculating vehicle forces and brake airflow is high, both in computational effort and time. Therefore, strategies to improve analytical and simulation effectiveness efficiency are critical to achieve the goal of transporting more cargo safely and economically. This work implemented and compared the computational cost of a parallelization method against a traditional single-thread approach. The first model is based on lump parameters, while the second use Navier-Stokes conservation equations assuming an isothermal environment. Both models used OpenMP to execute on multiple cores. This implementation resulted in an 80% reduction in model solution time, when compared with the traditional single-thread approach Aberto

As people spend more and more time inside, the quality of indoor air becomes crucial matter. This study explores the germicidal potential of two dark-operating germicidal composite materials designed to be applied for the indoor air disinfection under flow conditions. The first material, MnO 2 /AlPO 4 /γ-Al 2 O 3 beads, is a donor-acceptor interactive composite capable of creating hydroxyl radicals HO.. The second one is a ZnO/γ-Al 2 O 3 material with inter-cropped hexagons on its surface. To determine the antimicrobial efficiency of these materials in lifelike conditions, a pilot device was constructed that allows the test of the materials in dynamic conditions and agar diffusion inhibitory tests were also conducted. The results of the tests showed that the MnO 2 /AlPO 4 /γ-Al 2 O 3 material has a germicidal effect in static conditions whereas ZnO/γ-Al 2 O 3 does not. In dynamic conditions, the oxidizing MnO 2 / AlPO 4 /γ-Al 2 O 3 material is the most efficient when using low air speed whereas the ZnO/γ-Al 2 O 3 one becomes more efficient than the other materials when increasing the air linear speed. This ZnO/γ-Al 2 O 3 dark-operating germicidal material manifests the ability to proceed the mechanical destruction of bacterial cells. Actually, the antimicrobial efficiency of materials in dynamic conditions varies regarding the air speed through the materials and that static tests are not representative of the behavior of the material for air disinfection. Depending on the conditions, the best strategy to inactivate microorganisms changes and abrasive structures are a field that needs further exploration as they are in most of the conditions tested the best way to quickly decrease the number of microorganisms.

Background and objective The idiopathic interstitial pneumonias (IIPs) are diffuse parenchymal lung disorders that are associated with substantial morbidity and mortality. Early diagnosis and disease stratification of IIP patients are important because these are related with the treatment and prognosis. Idiopathic pulmonary fibrosis (IPF) and nonspecific interstitial pneumonia (NSIP) are two major distinctive pathologic patterns of pulmonary fibrosis. We researched the application of the fluid-structure interaction (FSI) to the respiratory system and compared the pulmonary acinus mechanics and functions in healthy and IIP models. Methods The human pulmonary alveolus is idealized by a three-dimensional honeycomb-like geometry, and a fluid-structure interaction analysis is performed to study the normal and diseased breathing mechanics. The computational domain consists of two generations of alveolar ducts within the pulmonary acinus, with alveolar geometries approximated as closely packed 14-sided polygons. Findings In a normal breathing cycle, the flow rate of the healthy model is significantly larger than that of the NSIP and IPF models. Similar trends are observed for the volume change and the maximum pressure drop. The flow rate and the volume change of the NSIP are almost the same as those of IPF. The maximum pressure drop of NSIP is 5.5% larger than that of IPF. There is a 47% decrease in the pulmonary acinus compliance for the NSIP and IPF compared with that of the healthy model. The acinus resistances of NSIP and IPF are higher than those of the healthy lung by 6.4~11.2%. In particular, the pulmonary acinus resistance of the NSIP lung is higher than that of the IPF lung by 4.5%. Conclusions Our study demonstrates the differences of air flow and lung function in the pulmonary acinus between the healthy and the IIP models. These changes in the lung are important considerations for early diagnosis and disease stratification in patients. Patient-based geometry can to be included in the computational models in future studies.

Filtering facepiece respirators (FFRs) and medical masks are widely used to reduce the inhalation exposure of airborne particulates and biohazardous aerosols. Their protective capacity largely depends on the fraction of these that are filtered from the incoming air volume. While the performance and physics of different filter materials have been the topic of intensive study, less well understood are the effects of mask sealing. To address this, we introduce an approach to calculate the influence of face-seal leakage on filtration ratio and fit factor based on an analytical model and a finite element method (FEM) model, both of which take into account time-dependent human respiration velocities. Using these, we calculate the filtration ratio and fit factor for a range of ventilation resistance values relevant to filter materials, 500–2500 Pa∙s∙m−1, where the filtration ratio and fit factor are calculated as a function of the mask gap dimensions, with good agreement between analytical and numerical models. The results show that the filtration ratio and fit factor are decrease markedly with even small increases in gap area. We also calculate particle filtration rates for N95 FFRs with various ventilation resistances and two commercial FFRs exemplars. Taken together, this work underscores the critical importance of forming a tight seal around the face as a factor in mask performance, where our straightforward analytical model can be readily applied to obtain estimates of mask performance.

This paper presents the research of interaction of air flow and melted material in production of fibrous materials. Correlations for calculation of air flow rate in different cross sections of a stream are acquired. The developed method of calculation of air flow rate at point of contact with stream of the melted polymeric material can be used in construction of blow heads models with a slot nozzle in production of fibrous products from different polymeric materials.

In the new Brickell City Center the public spaces between the retail shops are covered by an open steel glass structure. The primary structure consists of triangular surfaces which are inclined towards each other. Below this transparent rain protection the 3-dimensional shaped “Blades”, PTFE-covered continuous stripes, are arranged for sun shading. Eight of the in section triangular shaped “Blades” and two “Delta Beams” along the border vary in their dimensions and orientation to ensure the sun shading task in each position. One of the challenges aside extremely high wind loads was the almost invisible membrane fixation. The total length of the Climate Ribbon™ is over 200m.

Grain heap contains high-grade grain, weed and grain impurities. At the preliminary stage of grain processing, it is necessary to clean the grain heap and allocate the fraction of light waste grain impurities which are a valuable food for farm animals. This paper proposes a technical solution for the implementation of this process and derives a mathematical model thereof. The authors analyze the modeled process of grain impurities allocation from the fraction of light waste sediment in the area of the suction port flow fan. The results of modeling are verified by comparison to experimental data. It is found out that the results of theoretical studies fit the ± 10% tolerance of the experimental data difference. The agreement between the theoretic generated and the experimental results on the hypothesis on the samples belonging to the same general population based on the sign test is considered acceptable. The resultant mathematical model adequately describes the process of fractionation of light waste in the sedimentary area of the suction chamber in diametrical fan window.

Dust masks are widely used to prevent the inhalation of particulate matter into the human respiratory organs in polluted air environments. The filter of a dust mask inherently obstructs the natural respiratory air flows, and this flow resistance is mainly responsible for the discomfort experienced when wearing a dust mask. In atmospheric conditions seriously contaminated with fine dust, it is recommended that common citizens wear a dust mask in their everyday lives, yet many people are reluctant to wear a dust mask owing to the discomfort experienced when wearing it for a long time. Understanding of physical reasons for the discomfort is thus crucial in designing a dust mask, but remains far from clear. This study presents a technique to quantify the wearing comfort of dust masks. By developing a respiration simulator to measure the pressure loss across a dust mask, we assessed the energy costs to overcome flow resistance when breathing through various types of dust masks. The energy cost for a single inhalation varies with the mask type in a range between 0 and 10 mJ. We compared the results with the survey results of 40 people about the wearing comfort of the dust masks, which revealed that the wearing comfort crucially depends on the energy cost required for air inhalation though the dust mask. Using the measured energy cost during inhalation as a parameter to quantify the wearing comfort, we present a comprehensive evaluation of the performance of dust masks in terms of not only the filtering performance but also the wearing comfort. Our study suggests some design principles for dust mask filters, auxiliary electric fans, and check valves.

This study investigated the efficiency of a portable nitric oxide (NO) inhalation device through optimizing its design and structure. The portable rescue device could be used in clinical applications in outbreaks of viral pneumonia such as SARS. To reduce energy consumption for battery-powered portable usage, NO micro-channel plasma reactions induced by a continuous discharge arc were employed. A single-use airway tube could be combined with an intubation tube in clinical applications. In the experiment, a switching transistor controlled high frequency DC (12.5 kHz) was used to create a continuous discharge arc between two stainless steel electrodes (1-mm separation) after high-voltage breakthrough. A rotate instrument was employed to change the direction angle between the airflow and discharge arc, tube filled with Calcium hydroxide connected with gas outlet for reducing NO2, gas flow rate and input voltage were evaluated separately with concentration of NO and NO2/NO ratio. Results showed that a 2 L/min air flow direction from the cathode to the anode of electrodes (direction angle was zero) under 4 V input voltages produced 32.5±3.8 ppm NO, and the NO2/NO ratio reduced to less than 10%, stable output of nitric oxide might be convenient and effective for NO inhalation therapy. Modularization of the design produced a portable NO inhalation device that has potential for use in clinical applications as it is low cost, easy to disinfect, consumes low levels of energy and is ready to use.

The article presents an entropy-statistical analysis of losses in the mixing section of a central air conditioner. The temperature and humidity of the outdoor and recirculating air were measured. The methodology for determining losses using the entropy-statistical method is presented in the work. The calculation of losses in the mixing section of the central air conditioner due to the mixing of air flows depending on the flow rate of the supply and recirculation air as well as due to hydraulic losses. A comparative analysis of the results is carried out and the distribution diagrams of the component losses are presented. Proposed conclusions regarding the way to reduce losses.

A model of a variable air volume (VAV) system is developed that can predict air flow rates, fan pressure rise, and fan power consumption in response to changes in fan speed and damper positions. The system consists of a fan, ductwork, and a number of dampers, one in each VAV box. The model can be used for conducting simulation studies of how advanced control algorithms that seek to provide various services (energy efficiency, personalized comfort, and demand-side flexibility to the grid) may behave when deployed in a building with an existing climate control system, or to do model-based control computations for such services. Comparison of the model's predictions with experimental data from a small commercial building is presented for the single-zone version of the model. The multi-zone model structure is described, but its validation is left for future work. Due to the strong non-linearities in the steady state relation between inputs and outputs, and due to the fast transient response observed in experiments, the dynamic model is constructed to be of Hammerstein type, with a linear dynamic system in series with a static nonlinear model.

Рассмотрены алгебраические уравнения первого и второго порядков, свёртывающие комплекс метеорологических и географических показателей: температуру, давление, влажность и скорость потока атмосферного воздуха, азимут и высоту Солнца над горизонтом и другие характеристики географической точки в гиперповерхность обобщённых метеорологических показателей. В результате исследования уравнения свёртки установлено, что данная гиперповерхность имеет три положительных и один отрицательный индекс инерции, то есть на самом деле является гиперконусом второго порядка, центр которого движется по некоторой траектории в многомерном конфигурационном пространстве состояний метеорологической системы. Выделенные частные решения, отражают сочетания значений давления, влажности, скорости атмосферного воздуха и других факторов, отнесённых к географической точке с показателем температуры выше 10 градусов, имеющих особое значение для устойчивости продукционного процесса в сельскохозяйственном растениеводстве и формирования качества растительного сырья., Algebraic equations of the first and second orders are considered, which coagulate a complex of meteorological and geographical indicators: temperature, pressure, humidity and air flow rate, azimuth and height of the Sun above the horizon, and other characteristics of the geographical point in the hypersurface of generalized meteorological indicators. As a result of the study of the convolution equation, it has been established that this hypersurface has three positive and one negative inertia index, that is, it is in fact a second-order hypercone whose center moves along a certain trajectory in the multidimensional configuration space of meteorological system states. Dedicated private solutions reflect combinations of pressure, humidity, atmospheric air velocity and other factors related to a geographic point with a temperature index above 10 degrees, which are of particular importance for the sustainability of the production process in agricultural plant growing and the formation of the quality of plant raw materials. Qualitative characterization of the mutual influence of individual indicators of the flow of atmospheric air when they are systematized may be useful for developing indirect methods for assessing, refining or recovering meteorological observations, as well as predicting the production process in agricultural crop production.

The normal studies on air traffic departure scheduling problem (DSP) mainly deal with an independent airport in which the departure traffic is not affected by surrounded airports, which, however, is not a consistent case. In reality, there still exist cases where several commercial airports are closely located and one of them possesses a higher priority. During the peak hours, the departure activities of the lower-priority airports are usually required to give way to those of higher-priority airport. These giving-way requirements can inflict a set of changes on the modeling of departure scheduling problem with respect to the lower-priority airports. To the best of our knowledge, studies on DSP under this condition are scarce. Accordingly, this paper develops a bi-objective integer programming model to address the flight departure scheduling of the partly-restricted (e.g., lower-priority) one among several adjacent airports. An adapted tabu search algorithm is designed to solve the current problem. It is demonstrated from the case study of Tianjin Binhai International Airport in China that the proposed method can obviously improve the operation efficiency, while still realizing superior equity and regularity among restricted flows.

Penanganan pasca panen padi merupakan salah satu upaya untuk meningkatkan produksi padi, dengan semaksimal mungkin menekan kehilangan hasil panen. Salah satu faktor yang mempengaruhi kehilangan hasil panen padi adalah proses pembersihan gabah. Berdasarkan hal tersebut, diperlukan suatu upaya untuk mendapatkan proses pembersihan gabah yang optimal dengan cara menganalisis variabel yang berpengaruh pada proses pembersihan gabah. Penelitian ini bertujuan untuk menghasilkan suatu persamaan matematika untuk memprediksi besar sudut lempar gabah, mengetahui hubungan antar variabel yang mempengaruhi proses pembersihan gabah secara mekanis serta untuk mendapatkan variabel yang diperlukan dalam rancang bangun mesin pembersih gabah dengan media pembersih berupa aliran udara. Melalui pendekatan analisis dimensi diperoleh persamaan prediksi sudut lempar gabah ( θ ) sebagai fungsi dari bulk density gabah ( ρ ), diameter saluran udara ( D ), laju aliran udara ( V ), kapasitas ( Kp ), diameter gabah ( d ), kadar air gabah ( α ) serta jarak saluran udara dan gabah jatuh ( l ) yaitu : θ = 0,0661.( ρ. d^2.V/Kp )^0,643 . (dx α/t)^0,0618 Hasil validasi persamaan prediksi sudut lempar gabah menunjukkan bahwa hasil prediksi tidak berbeda nyata dengan hasil observasi sehingga persamaan prediksi yang dibuat dapat diterima. Hasil simulasi persamaan prediksi menunjukkan bahwa diameter saluran udara dan jarak saluran udara saat gabah jatuh memiliki pengaruh tetapi tidak signifikan terhadap besarnya sudut lempar gabah, sedangkan laju aliran udara dan kapasitas memiliki pengaruh yang signifikan terhadap besarnya sudut lempar gabah. Throw Angle Analysis of Grain on Grain Cleaning Machine With Air Flow Abstract . Post-harvest handling of rice is one of the efforts to increase rice production, with maximum pressing crop yield loss. One of the factors that influence the loss of the harvest is the process of cleaning of the grain. Based on this, we need an effort to obtain optimal grain cleaning process by analyzing the variables that affect in the grain cleaning process. This research aims to produce a mathematical equation to predict the large grain throwing angle, determine the relationship between the variables that affect in the mechanical cleaning process grain and to obtain the necessary variables in the design of grain cleaning machine with cleaning media in the form of air flow. Through the dimensional analysis approach derived prediction equations throwing grain angle (θ) as a function of grain bulk density (ρ), the diameter of the airways (D), the air flow rate (V), capacity (Kp), grain diameter (d), water content grain (α) and distance airways and grain fall (l), namely: θ = 0,0661.( ρ. d^2.V/Kp )^0,643 . (dx α/t)^0,0618 The result of prediction equation from grain throwing angle show that prediction result is not different significant with observation result. Simulation result of prediction equation show that the diameter of airways and distance airways when grain fall has influence but not significant on the value of grain throwing angle, whereas the air flow rate and capacity has significant influence on the value of grain throwing angle.

Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers. The paper presents the analysis of results of the investigations concerning the influence of various constructive solutions of the air-water mixers on hydraulic operating conditions of the air lift pump. The scope of the investigations encompassed the determination of characteristics of delivery head and delivery rate for three types of air-water mixers applied in the constructed air lift pump. Using the obtained results, the efficiency of the three types of air-water mixers applied in this air lift pump was determined. The analysis was carried out and there was checked whether the improved analytical Stenning-Martin model can be used to design air lift pumps with the air-water mixers of these types. The highest capacity in the water transport was reached by the air lift pump with the 1st type air-water mixer, the lowest one – with the 3rd type air-water mixer. The water flow in the air lift pump increases along with the rise in the air flow. The lower are the hydraulic losses generated during flow of the air flux by the air-water mixer, the higher is the air lift pump capacity. Along with the rise in the water delivery head, the capacity of the air lift pump decreases. The highest efficiency is reached by the air lift pump with the 1st type air-water mixer, the lowest – with the 3st type air-water mixer. The efficiency of the air lift pump for the three investigated types of air-water mixers decreases along with the rise in air flow rate and water delivery head. The values of submergence ratio (h/L) of the delivery pipe, calculated with the use of the improved analytical Stenning-Martin model, coincide quite well with the values of h/L determined from the measurements.

Background We assessed whether a short training, effective in a high resource country, was able to improve the quality of face-mask ventilation (FMV) in a low resource setting. Methods Local healthcare providers at the Centre Médico-Social, Kouvè, Togo were asked to ventilate a neonatal leak-free manikin before (time—t1) and after (t2) a two-minute training session. Immediately after this section, a further two-minute training with participants aware of the data monitor was offered. Finally, a third 1-minute FMV round (t3) was performed by each participant. Ventilatory parameters were recorded using a computerized system. Primary outcome was the percentage of breaths with relevant mask leak (>25%). Secondary outcomes were percentages of breaths with a low peak inspiratory pressure (PIP35 cm H2O). Results Twenty-six subjects participated in the study. The percentage of relevant mask leak significantly decreased (p35 cm H2O was 19.5% (SD 32.8%) at t1 and 39.2% (SD 37.7%) at t2 (padj = 0.27; β = +0.61, SE = 0.36) and significantly decreased (padj = 0.01; β = -1.61, SE = 0.55) to 6.0% (SD 15.4%) at t3. Conclusions A 2-minute training on FMV, effective in a high resource country, had a positive effect also in a low resource setting. FMV performance further improved after an extra 2-minute verbal recall plus real time feedback. Although the training was extended, it still does not cost much time and effort. Further studies are needed to establish if these basic skills are transferred in real patients and if they are maintained over time.

Wind-driven air infiltration has been recognized among the major reasons for energy loss in buildings, and the impact to energy efficiency under steady conditions has been reported and issued as part of many building codes. The nearly zero-energy building demand makes uncontrolled leakage paths even more undesired and creates the need for further investigation of their behavior under unsteady wind conditions. The present numerical study examines the role of wind gustiness on instantaneous infiltration rates of a low-rise building. For this purpose, two levels of gust frequency Ω have been simulated, expressed as a sinusoidal factor in the wind profile formula. In parallel, a ratio α is employed to represent seven different cases of external leakages distribution, while five scenarios of compartmentalization and internal leakages shows the impact of the latter on the dynamics of building air exchange rates. The results indicate that higher wind gustiness results in higher ACH, marking out gusts as a potential critical factor under unsteady climate conditions. The infiltration rates shown in relation to the leakage distribution ratio α provide arguments for the importance of the detailed detection of external leakages while the comparison of the different internal-volume-scenario highlights the key-role of internal leakages control towards a drastic reduction of infiltration rates.