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Airway management is a priority to any caregiver in a trauma scenario. The current clinical gold standard for airway securement is endotracheal intubation (ETI), which involves placement of an endotracheal tube into patient tracheas and pneumatically expanding a cuff for securement. Incorrect performance of this delicate and complex procedure poses significant risks to patients, as excessive force and leverage during insertion can damage sensitive airway tissues, especially when performed by less-skilled providers or executed in difficult airway situations. The present study investigated the development of a bioinspired mechanical platform termed the Digital Extenders, which is capable of augmenting a provider’s reach for ETI. A prototype that could apply an output force of at least 20 N was designed for comparative analysis versus current clinical approaches. Performance analysis studies utilized an innovative instrumented mannequin model to compare force employed during intubation with the Digital Extenders versus direct laryngoscopy and digital intubation. Resulting data showed that there is an important reduction in applied force at the base of the tongue using the novel Digital Extenders platform; such a reduction of applied force is important in enabling the provider to secure the airway, causing less trauma to the patient. In addition, the use of the Digital Extender protects the provider’s digits from patient bite reactions typical from intubation when the patient is not sufficiently sedated. These study results motivate continued development of the Digital Extenders as a less traumatic approach to ETI. Future consideration may investigate challenges in mannequins’ biomimicry of physiological properties.

A differential equation was established based on the force analysis of the gel extinguishing agent micelles fired by the fire gun to analyse the characteristics of the movement of micelles by considering the resistance of movement. Runge-Kutta algorithm was used to solve the differential motion equation of micelles to predict the movement trajectory of micelles when launching at different elevation and depression angles. The results showed the predicted trajectory was in good agreement with the real ball movement trajectory when elevation angle was smaller than or equal to 60° and the range error was controlled within ±8%.

In this work, a grinding force model has been proposed and a correlation between the analytical model and the experimental grinding forces obtained during finishing of plasma sprayed ceramic coatings has been investigated. Thermally sprayed ceramic coatings have low fracture toughness and develop micro brittle fracture under moderate mechanical loading. In this investigation, grinding of air plasma sprayed alumina, zirconia, and titania coatings were studied theoretically and experimentally. It was observed that the ground surface contained micro-cracks and debris of irregular fragmented chips owing to the micro-brittle fracture. A grinding force model is proposed to incorporate the fracture behavior of the ceramic coating. This was substantiated through experimental values showing low grinding forces.

Aim To develop the mathematical model for root canal preparation using Endodontic file. Method The process of obturation consist of the filling of the root canal cavity using heated and softened gutta-percha to get the fluid tight seal in between the canal wall and filled gutta-percha. Any obturation process to perform before it requires the preparation of the root canal which involves the removing dead tissue, substrates and debris from the decayed root canal. The various geometric parameters viz. Taper, relative angle for orientation of cross-section between two planes, pitch and polar symmetry constant of the Endodontic file etc. Geometric parameters are derived. The various performance parameters like Endodontic file life assessment, cutting force components (tangential and normal), substrate removal rate, torque exerted by Endodontic file etc are also derived successfully. The Endodontic file life is estimated based on two approaches viz. speed and volumetric wear approach. Conclusion The mathematical model described is helpful for the Endodontic experts, researchers, design engineers etc. However the applicability of the described mathematical model limited to assumption of study. The gap between root canal to be prepared and Endodontic file is zero while preparation. The Endodontic file weight, speed of rotation and substrate removal rate is assumed to be constant. The mathematical model for Endodontic file discussed above proved to be efficient tool for studying the root canal preparation. The various geometric parameters and the various performance parameters are derived.

The basic mechanism of electrostatic spinning is rapid whipping of charged jet. An ideal model was established for the key part of electrostatic spinning mathematical model, which is visco-elastic behavior model of the unstable section of charged jet. Through mechanical analysis of the viscoelastic behavior model and calculation of its governing equations, the physical and dynamic properties of the unstable section of the charged jet in the three-dimension Cartesian coordinate system were obtained. It will have a theoretical effect on the development of electrostatic spinning technology.

Assembly-level geometric errors such as backlash, center distance errors and shaft misalignments may adversely affect the operation of a gear train. The tolerance analysis method proposed in the paper estimates these errors from tolerance specifications on gears and mounting parts (shafts, bearings, housings). The problem is solved by analogy with an equivalent problem of force analysis: on a properly defined structure, external forces correspond to the assembly-level error, and calculated internal forces and support reactions provide the sensitivities of part tolerances on the total error. Previously developed for generic assemblies, the approach proves especially simple for gear systems compared to existing methods of tolerance analysis, as it relies upon structural analysis procedures that are customary in mechanical design. The method based on static analogy includes a two-level classification of geometric errors, which helps overcome the complexity of tolerance analysis problems for gearings. Two examples of gear trains of different types and configurations are presented to demonstrate the calculation procedure and verify its correctness by comparison with geometric considerations.

To achieve the qualitative and quantitative damage expression, coal samples within original cracks were selected to conduct uniaxial compressive loading experiments. During this process, acoustic emission signals were collected by AEwin Test for Express-8.0 and cracks evolution were captured by video camera. The results showed that the larger the initial damage, the lower the uniaxial compressive strength and elastic modulus of coal samples. When coal samples were subjected to uniaxial compression, the primary cracks closed firstly. Then friction phenomenon might generate due to sliding along the cracks surface and the deflection might occur at the center of cracks. Finally, original cracks expanded and new cracks formed and propagated to cause sample fracture, all which leaded to acoustic emission events. AE counts and accumulated counts changed with time, which corresponded well with stress–strain. Therefore, the value of AE counts and the trend of accumulated counts qualitatively explained the damage evolution laws of loaded coal. Further, based on the damage theory of acoustic emission counts, the quantitative damage variable was proposed and calculated. What’s more, the force analysis near the cracks surface at the initial loading process was explained and the cracks dynamic evolution during the whole compressive loading process was discussed. It was helpful to understand the damage evolution mechanism of coal samples.

Investigating the behavior of droplets impacting on stainless steel wire mesh is of great importance. Previous studies focused on the impact phenomena of a whole wire mesh, without detailed function of each composing unit. In this work, the impact on two basic units of the single fiber and the intersection of two crossing fibers was systemically investigated. The dispersion processes of the droplets were recorded by a high-speed camera at various conditions of the droplet velocities, initial droplet sizes, and impacted object shapes. Three dripping modes of one-drop, double-drop, and ligament were observed when droplets impact on one single fiber. Two disintegration modes of four-part and two-part were found with crossing fibers. Correlations of the maximum spreading length of the droplet on the fiber of wire mesh were proposed, and the predicted values were in a good agreement with the experimental values. The mathematical models of the boundaries between different modes were established based on the force analysis of the droplet impacting on the mesh units.

A generic evacuation model is developed based on the behavioral characteristics of passengers during bus fires. Inspired by hydrodynamic mechanisms, the proposed particle-based force-driven model is built using force analysis of evacuees and analogs the movement of people as fluid motion. Several modules are developed to characterize evacuees’ preferences for varying exits, aggregated behavior of groups, and effects of driver. The Smoothed Particle Hydrodynamics (SPH) methods are applied to solve the proposed model using smoothed kernel functions. Experiments are conducted to calibrate and validate the proposed model based on observed evacuees’ behavioral characteristics, such as evacuation time, evacuation speed under different scenarios in terms of bus capacity, and the interaction between evacuees. The results of the study will contribute to a better understanding of bus evacuation options, improved design of bus vehicles to cope with internal fires, and the development of appropriate policies and regulations for bus passenger evacuation in response to fires. The proposed method can also be readily applied to other related fields with minor modifications.

The spatial layout of the steel industry has an impact on the regional atmospheric environment. In this study, the steel industry evolution model and the driving force analysis model were combined to analyze the evolution of spatial layout of the steel industry in China and the driving factors of this evolution. In addition, the WRF-SMOKE-CMAQ model was used to analyze the spatial dynamics of SO2 emissions from the steel industry. Our analysis presents the evolution of the steel industry in China in four stages: policy-determining, resource-oriented, economic promotion and market-oriented stage. The change in the spatial layout of the Chinese steel industry resulted in a continuously decreasing trend of pollutants in temporal characteristics and a decreasing share of emissions in North China and a continuous growth in East China in spatial characteristics. Our simulation shows that, by 2025, the pollutant SO2 emission concentration will migrate to the southeast, subject to market-oriented factors.

This paper investigates the heterocoagulation between microcrystalline graphite and quartz particles using the in-situ particle size distribution and zeta potential distribution measurements. It was found that the heterocoagulation was significant at acidic pH but negligible at alkaline pH. Additionally, the heterocoagulation was eliminated by the addition of sodium hexametaphosphate (SHMP). The heterocoagulation mechanism was accounted for by the interparticle force analysis based on the Deyaguin-Landau-Verwey-Overbeek theory. The separation efficiency of the mixture of graphite and quartz was improved when pH was modified to alkaline or sodium hexametaphosphate was added due to the inhibition of heterocoagulation.

Background/purpose: The focus of this study was to find a correlation between the forces and vibrations during root canal shaping. This can be used to predict the fracture of the self-adjusting file (SAF) in root canal shaping. Materials and methods: Forty J-shaped resin blocks were used in this study. Simulated root canals of resin blocks were prepared with the SAF. Force and vibration during root canal shaping were measured by dynamometer and accelerometer respectively. The recorded time domain signal of force and vibration were transformed to frequency domain signals. Frequency domain signals had been used for correlation study between force and vibration amplitude. The root mean square (RMS) value of force and vibration signature for new file and file just before failure were statistically compared using t-test at 95% confidence interval (CI). Results: Vibrations generated during root canal shaping exhibited positive linear correlation (r = 0.9173) with force exerted by the SAF on the root canal. It means vibration has strong correlation with force. The RMS values of force and vibration increase significantly (P

China's chemical industry has greatly altered the processes that contribute to reactive nitrogen (Nr) creation and Nr emission. However, the fluxes, fates and environmental consequences of Nr produced by the chemical industry remain poorly understood and unquantified. We report here that Nr creation and Nr emission by the chemical industry increased 47- and 37-fold from 1963 to 2015, respectively. Nr fixation in the chemical industry mainly results from the production of N fertilizer, but Nr fixation by fossil fuel combustion and chemical N products (except N fertilizer) has rapidly increased over the past 15 years. Meanwhile, the manufacture of raw chemical materials and chemical products are the main contributors to waste Nr production. Driving force analysis of Nr creation and Nr emission shows that population growth has the largest positive effect, while urbanization also has varying degrees of impact. Additionally, we propose some policy suggestions to reduce the environmental impact of Nr emissions from the chemical industry based on a brief future perspective of Nr creation and Nr emission. These findings will provide policy makers with an integrated view of Nr metabolism and environmental damage to address the significant challenges associated with reducing emissions in the chemical industry.

Applying prestressing techniques increases the load carrying capacity of girders, leading to substantial saving in construction material. In addition, prestressing a steel girder reduces its deflection under external loads, and thus, enhances its flexural behavior. The aim of this study is to use a finite-element formulation to verify the effectiveness of the prestressing technique with respect to the flexural behavior of a steel plate girder. The strength of two steel box girders is tested, one with prestressing (prestressed girder) and one without (control girder). Based on experimental results, a theoretical model is proposed for predicting the flexural resistance of a steel box girder with external tendons. To improve the calculation accuracy, finite-element formulation is applied to prestressing and external loading stages of the girder and external tendons, which are regarded as composite structures, and the interactions between them are fully considered. The friction between tendons and deviators is considerably small. Therefore, the friction resistance between the tendons can be neglected during the force analysis. The strain in the prestressed girder is distributed linearly along its height, indicating that the calculation performed using the plane section assumption is consistent with the actual situation for the same external load. The experimental and theoretically calculated values of strain in the bottom plate of a steel girder and tension force increment for deflections at mid-span and quarter span are in good agreement. This indicates that the finite-element formulation proposed in this study is correct and efficient.

Thousands of spherical fuel elements are transported pneumatically in pipelines in a pebble bed reactor every day. The motion of the fuel element has a strong influence on the efficiency and reliability of the reactor. The motion is determined by the force condition of the fuel element which is determined by the characteristics of the flow field in turn. Thus, it is of great significance to analyze the characteristics of the flow field and the force conditions of the fuel element. In this paper, we carry out simulations of the flow field with a structured mesh based on CFD (computational fluid dynamics). We analyze the effect of the motion and position of the fuel element on the flow field. Then we accomplish the force analysis of the fuel element in the flow, and acquire the fitting formulae of the force and torque on the fuel element. The experiment was performed on the experimental platform. The experimental results are in agreement with the theoretical analysis and verify its accuracy. This research may provide an important rationale for the dynamic and kinematic analysis of the fuel element pneumatic transportation as well as the basis for the stable operation of the reactor.

Single point incremental sheet forming (SPIF) is one of the latest near-net shape manufacturing technologies in which sheet metals are subjected to a step by step plastic local-deformation to form the final geometry. In this regard, many researchers have made an attempt to increase the flexibility and accuracy of the process by deforming the sheet at micro scales under the name ‘Single Point Micro Incremental Forming (SPMIF)’. In this paper, it is attempted to investigate the forming limits and forming forces in micro-features formed by SPMIF on stainless steel foils of 0.04 mm thick. A 3-axis CNC vertical milling machine was used to deform the foils with the hemispherical end tool tip diameters of 200 µm and 300 µm. The effect of rotational speed on the forming forces and forming limits of stainless steel foils has also been reported. Taguchi’s L18orthogonal array was used to analyze the effect of spindle speed, tool tip diameter and incremental step-down. It was found that forming forces decreases with the increase in spindle speed and the process was feasible enough to produce pyramids in micro-scale with higher forming limits than conventional forming.

Based on a data envelopment analysis framework, this study develops an indicator termed as carbon-weighted economic development (CWED) covering the dimensions of energy, environment, economy and resources to measure the economic development performance in a carbon-emission conscious economy. As an empirical application, the proposed approach is applied to a case study of 30 provinces in China. In addition, to identify the driving forces underlying low-carbon economic development in China, we analyze the endogenous interactions and dynamic behaviors between CWED, Foreign Direct Investment, foreign trade, industrial structure, local fiscal expenditure and energy consumption structure using a panel vector auto-regression model. The main findings show that, (1) adjusting industrial structure by vigorously developing the service industry and reducing the coal energy share in the primary energy consumption structure are the two most effective approaches to improve CWED in both the short-run and long-run; in return, CWED has positive feedback effects on both approaches in the long-run; (2) increase of the fiscal expenditure has a short-term positive effect on CWED; (3) FDI has an indirect negative effect on CWED in the long-run and foreign trade has an indirect positive effect on CWED in the short-term.

According to the principle of the gear overall size as small as possible, the structural analysis of multistage micro-planetary transmission is carried out. It is found that a 2K-H multistage micro-planetary gear reducer meets with the principle requirement. On this basis of the torque, power balance equations and force analysis of the basic members, the power distributions of a 2K-H multistage micro-planetary gear reducer are analyzed under considering power losses or not, the overall transmission efficiency calculation of a 2K-H multistage micro-planetary gear reducer is more intuitive and easy to operate. Meanwhile, it indicates a direction for further power losses analysis of multistage micro-planetary transmission.

New numerical strategies that reconsider tubing force analysis (TFA) in connection with buckling induced lock-up are presented and applied. The strategies introduce new visualizations of downhole instabilities in coiled tubings (CT) for the entire run-in-hole (RIH) process. Most extended reach interventions seek to reduce compressive forces experienced by the CT through usage of lubrication, vibrations or tractors, but little attention has been given to stabilizing initiatives that prevent buckling. A stabilizing initiative is anything that increases the critical helical buckling load of the CT, for example a reduction of radial clearance between CT and wellbore. The strategies presented allow us to (1) evaluate the gain in CT reach from stabilizing initiatives, and (2) automatically determine the minimum requirement for a stabilizing initiative that will bring the CT to the desired operational depth, when it is applied optimally along the length of a CT/wellbore. Thus, the strategies promote investigations of novel stabilizing solutions that can complement existing extended reach technologies. The developed TFA algorithm is validated against field data and the strategies are utilized on a wellbore in the Danish North Sea. The investigation showed that a stabilizing initiative that increases the critical helical buckling load by 31% when introduced into 35.57% of the wellbore length will extend CT reach from 69.72% to 100% into the payzone. With these strategies in place we present a new approach to optimize well utilization.

In coal mining, coal seams often contain several normal coal layers and deformed coal layers in the same region. However, the existence of deformed coal may promote the occurrence of coal and gas outbursts. To analyze the role of failure of different combinations of deformed coal on coal and gas outbursts, force analysis of normal and deformed coal combinations containing gas was carried out, and the expressions of interfacial stress induced by uncoordinated horizontal deformation were first derived in this paper. The results showed that the additional interfacial stresses are affected by the external stresses, internal gas pressure, gas sorption-induced swelling deformation and mechanical parameters of coal and that the additional interfacial stresses on the normal coal and deformed coal are equal and opposite. Then, based on the Mohr-Coulomb criterion and uncoordinated deformation, the mechanical failure mechanisms and forms of combinations containing gas under ideal conditions were analyzed. We found that there are seven failure forms for the combination containing gas, and in most cases, the destruction of the combination is caused by the structural failure of deformed coal. Finally, the failure mechanisms of the combination due to mining were discussed using the parameters from the Qinshui Basin. The results showed that failure is more probable at the interface between the deformed coal and normal coal bodies and that the existence of deformed coal can promote the damage of normal coal. These research results can help us to better understand the role of mechanical failure in coal and gas outbursts within combinations, and provide a theoretical basis for the control of coal and gas outbursts.

Drainage and deformation of the intervening film can arguably represent the dynamic nature of colliding soft matters. The development of an interaction force analysis between soft interfaces helps to probe the drop deformation and the interfacial properties. Based on the SRYL model, the fluid flow inside the droplet and the convection-diffusion of the surfactant at the oil-water interface is coupled to model the distribution of a non-ionic surfactant (Span80) during drop deformation using AFM. This study quantifies the in situ interfacial concentration with a trace amount of surfactant at the interface and indicates its effect on the interaction forces between two immersed oil droplets in an aqueous solution.

The Double disk magnetic abrasive finishing process (DDMAF) poses better finishing characteristics while finishing paramagnetic thin work piece, when compared to plain magnetic abrasive finishing. This is due to the significant change in the behaviour of the flexible magnetic abrasive brush (FMAB) formed in two cases under similar conditions. Observing and comparing the behaviour of FMAB in action visually is a difficult task. However, FMAB average behaviour can be understood by observing the force signature. Thus present work aims at developing a setup that can be used to capture force signature for the two cases and then understand the FMAB behaviour. The present work present the FMAB force signature obtained while performing finishing with MAF with single disk and double disk. The force signature and the basic magnetic principle have been used to understand the FMAB behaviour and thus understand implications on the finishing process.

The liquid entrainment process at the vertical up tee branch is widespread in mass and heat transfer applications. Existing liquid entrainment models mainly apply to T-junctions with small diameter ratios of branch to main line (d/D), which are unable to predict the liquid entrainment under large d/D conditions. The models of liquid entrainment onset and entrainment rate are developed under reasonable assumptions. The entrainment onset model was developed based on the wave theory, force analysis and potential flow theory. The Bond number is innovatively introduced into the model to represent the effect of surface tension acting on the entrainment onset. The model is compared against the relevant experimental data which shows good agreement. In the modeling of the entrainment rate, the key parameters are obtained by nondimensionalizing the conservation equations governing the liquid entrainment process, and the constants in the model are determined by genetic algorithm. The model agrees well with existing experimental data.

A new-type plugging coated particle system was investigated which is applied in high temperature & salinity reservoir, the temperature up to 300 ℃ and salinity up to 250,000 mg/L. To analyze these factors, based on adhesion feature of the particle, a series of experiments were performed to investigate properties of particle and its suspension system, including dynamic plugging experiments, etc. The results showed that the particles can adhere together under certain temperature up to 140 ℃. Moreover, the particle suspension, including HPG system and foam system, were screened based on suspending time. In addition, we selected four parameters, including salinity, injection rate, permeability and mass fraction, to measure plugging ability of system. Meanwhile, the visual microscopic models and glass sand-pack models were designed to observe directly particle flow in the porous media. Finally, the force analysis of particles at some special locations in the models was simulated by COMSOL Multiphysics. Experimental results confirmed the essential characters of new-type particle and indicate that this plugging system had excellent plugging performance in high temperature & salinity environment. The particle migration had strong correlation with permeability and the particle had impacted on the original structure of mineral. The process of packing was accelerated and repeated. Besides, keeping the particle single and improving material strength would promote plugging effects. The evaluation and mechanism research of new type plugging particle could provide guidance for plugging agent selection in high temperature and field development project designing.

By inserting a vibrating tube into a static grain layer, the grains can climb along the tube, which presents a new way to convey grains continuously. In this study, both tubes with different sizes and cross-section shapes are used to probe the effect of geometry on climbing motion of grains. Under same vibration strength, grains in small diameter tube can climb directly into an equilibrium height. The grains in large diameter tube can’t climb directly. However, if enough grains are initially filled in the tube to a certain height, the grains can climb much higher. The grain climbing is more sensitive to the tube size rather than shape of tube cross-section. With same tube diameter, the climbing motion becomes difficult with increase of grain diameter. Consistent with the experimental results, a model based on force analysis is presented.

In order to know the force evolution during the cold pilgering process for Zircaloy-4 tube, rolling forces and axial forces were investigated by both experimental and finite element methods. The material behavior of the Zircaloy-4 tube used anisotropy yield function Hill48 and hardening law which can describe the deformation after necking. It can be concluded that the simulation results coincided with those from experiments. Based on the verificated FE model, the effect of friction coefficient, feed rate and rolling speed on the rolling force and axial forces were studied. From the results, friction coefficients have less effect on the rolling force, but play an important role on the axial forces of tube and mandrel. There is an positive correlation between the feed rate with the forces. With the increase of the feed rate, the forces are enhanced. While the higher is the rolling speed, the lower are the rolling force and axial forces because of the temperature-effect.

The linear driving force (LDF) model has been used to study adsorption dynamics in many gas and liquid phase applications and is particularly useful in the simulation of cyclic sorption operations. It is computationally a simpler alternative to the more complex models that use partial differential equations to represent diffusion within the sorbent particle. In this study, an LDF model that takes into account sorbent particle size distribution (PSD) within the adsorber is developed to study adsorption dynamics in fixed-bed adsorbers with different geometries and layering of particles of different sizes. Phenol and 2, 4-dichlorophenol (DCP), two trace contaminants in water supplies and wastewaters with differing adsorption characteristics, are studied in different adsorber configurations to determine the effects of bed geometry on bed capacity utilization. The convergent tapered stratified bed with eight granular activated carbon (GAC) particle sizes was found to enhance bed capacity utilization by 20% and 50% respectively for phenol and DCP over that of conventional stratified cylindrical bed adsorbers. The LDF model was found to provide good prediction and representation of adsorption dynamics in stratified fixed-bed adsorbers at much reduced computational effort. Sensitivity analyses indicate that the adsorption affinity of solute, bed geometry, and particle stratification play key roles in the enhancement of bed capacity utilization in fixed-bed adsorbers.

Reducing food losses (FL) is a promising way of improving food security. This is much more urgent for the developing world with a high level of food insecurity. However, driving factors contributing to the changes of FL are poorly understood. Here, we report on an investigation into the contribution of five potential driving factors to FL in Cameroon between 1994 and 2013, using a Logarithmic Mean Divisia Index (LMDI) approach. The results showed that FL in Cameroon has increased more than 4 fold during the study period. The increase of FL per unit crop production (intensity effect) contributed the most to increase FL (36.87% of the total change), followed by the increase of per capita crop consumption, i.e. supply scale effect (34.55%), population growth (26.72%), and changes of crop production structure, i.e. structure effect (5.079%). Only the dependency on self-production (self-sufficiency effect) contributed to decrease FL (3.22%).

Gold films with the thickness of 360 nm were deposited by electron beam evaporation. Post deposition annealing under 100–400 °C in ambient atmosphere was performed to the films to study the effect of annealing on the microstructure and residual stress stability of the films. After annealing, a combined process consisting of natural placement and thermal holding under 80 °C was conducted. Evolution of residual stress in this process was investigated. Results show that stability of the residual stress of gold films increased after annealing, the stress level also increased. SEM and STEM observation revealed that for annealing temperature of 175 °C and below, microstructure change of the films was mainly manifested by the voids elimination. For annealing temperature higher than 175 °C, besides of the void elimination, grain coalescence occurred and cross grain twins formed. Mechanism of the residual stress evolution was discussed based on the driving force analysis.

Aimed at finding out the influence degree of temperature, strain rate, water to cement ratio (w/c ratio) and maximum aggregate size on dynamic behavior of cement concrete, an orthogonal test on dynamic compressive strength of cement concrete applying a self-designed low temperature split Hopkinson pressure bar (SHPB) apparatus has been conducted on 8 groups of cylindrical cement concrete specimens (74 mm diameter and 34 mm thickness). The dynamic compressive strength of concrete specimens with different w/c ratios (0.5, 0.6) and maximum aggregate sizes (12 mm, 22 mm) have been tested at different temperatures (28 °C, 0 °C, −15 °C, −30 °C) and strain rates (33.5 s −1 , 46.7 s −1 ). The influence sequence of factors is: temperature > strain rate > w/c ratio > maximum aggregate size. According to the results of orthogonal test, a further experimental study concerning the influence of temperature (28 °C, 0 °C, −15 °C, −30 °C, −45 °C, −60 °C, −75 °C) and strain rate (34.33 s −1 , 44.25 s −1 , 63.18 s −1 ) on dynamic compressive strength of concrete has been conducted on 21 groups of cylindrical specimens. Also a mechanical calculation model has been built for force analysis. The results demonstrate that: When −75 °C

In this article threaded tool joints of gas sealing drill pipes, which are exposed to different tightening turns and tension load, are analyzed using an elaborate finite element modeling through the use of MSC.Marc13.0. The corresponding mechanics model is also established and the reliability of the model is verified by finite element simulation and full scale test. Some conclusive results have been drawn from the analysis including that the force distribution of the gas sealing joints is quite different from the API standard one, and the metal seal structure can greatly improve the seal performance of the joint under tension load. Research also shows that reasonable tightening turns can effectively reduce the thread axial load growth amplitude under the tensile load as a result improving the fatigue life of the tool joints.

A hydrophobic ratchet which consisted of teeth with gradient inclination was prepared in this work. The dynamic behaviors of resonant drops on the ratchet were experimentally investigated using a high-speed camera. According to our results, there are four types of behaviors of a resonant drop on the ratchet, including deformation in situ, wriggling, jumping and breaking up. For a wriggling or jumping drop, the drop can move directionally from the big to small inclination area. A new method to manipulate drop motion is proposed through combining the ratchet with vertical mechanical vibration. Moreover, the motion mechanism is presented on the basis of force analysis. Besides, the effects of amplitude, initial position and drop size on the drop acceleration and velocity are also discussed.

The separation characteristics of the gas-liquid cylindrical cyclone (GLCC) has been investigated by experiment and numerical analysis. The droplet size and phase distributions were measured using Malvern RTsizer and electrical resistivity tomography, respectively. The Discrete Phase Model was used to numerically analyze the swirling hydrodynamics. The results showed that the separator with strong swirl intensity would not necessarily get better separation performance, and the nozzle with Ne = 5.9 performed best. The small and medium droplets tended to initially coalesce and subsequently break up with increased gas superficial velocity, whereas they always tended to coalesce with increased liquid superficial velocity. ERT measurement results proved the existence of the flow reversal for the gas core. Finally, a droplet migration model was developed based on the force analysis of droplet and the swirling hydrodynamics, which accurately predicted the separation performance of GLCC. These results can be used in the design of the GLCC.

In China, as a kind of important precursors to cause PM2.5 and O3 pollution, nitrogen oxides (NOX) have attracted a large attention. From the perspective of electricity-related NOx generation, the aggregate nitrogen oxides generation intensity (ANI) is decomposed temporally and spatially based on the LMDI method. At the country level, ANI in China dropped significantly from 2.90 g NOX/kWh to 2.15 g NOX/kWh from 2000 to 2016. The temporal and spatial decomposition results showed that the major driving forces are the clean energy penetration (Ucp) and thermal power generation efficiency (Uint), which decreased ANI by 10.5% and 7.74% during the study period, respectively. Ucp in the southwestern, central and northwestern regions were the main contributors for ANI reduction. Uint in the eastern region was the main contributor in reducing ANI. Based on our findings, it is suggested to provide different NOX emission reduction policies for different provinces. Thus, these approaches will improve initiatives of reducing NOX emission from source.

A network model is developed to simulate the formation impairment process due to the capture of suspended particles in injected water, in which two paramount capture mechanisms—size exclusion and direct deposition—are taken into account. Based on the force analysis of each particle, an alternative capture criterion for direct deposition is proposed and incorporated into this model. The sensitivities for different factors are analyzed, such as the particle concentration in injected water, the pressure gradient placed on the network, the particle and pore–throat size distribution, and the fluid viscosity. The results exhibit very good agreement when compared with previous experimental data, which proves that this network model can be successfully used to reproduce the basic physical essence of the decrease in permeability and is efficient for studying the effect of different factors on the fine migration and its consequent formation damage. Furthermore, simulations are also conducted using the conditions under which the injected water is filtered before being injected into the network, which indicates that the pre-filtration process provides an effective tool for lowering or decaying the formation impairment.

Although the magnitude of the surface tension is often negligible in macroscale, capillarity-induced phenomena play an essential role in driving the motion of droplets. In this study, we conduct several experiments on the motion of an oil droplet near the meniscus between the wall and the horizontal water surface. The two cases when the water is pure and when it contains surfactant are both investigated. The results show that the oil droplet is repelled by the meniscus when the water does not include surfactant, and on the opposite it is attracted to the wall when there is surfactant added in water. We then carry out force analysis and energy simulation, which verify the experimental observations. These analyses provide inspirations for the design and fabrication of microfluidic devices, microreactors, and chemical sensors, and also pave a new way to oil collections in petroleum engineering and biomimetic design.

Downhole vortex drainage gas recovery is a new gas production technology. So far, however, the forces and motions of liquid phase in the swirling flow field of wellbores during its field application have not been figured out. In this paper, the forces of liquid droplets in the swirling flow field of wellbores were analyzed on the basis of two-phase fluid dynamics theories. Then, the motion equations of fluid droplets along axial and radical directions were established. Magnitude comparison was performed on several typical acting forces, including Basset force, virtual mass force, Magnus force, Saffman force and Stokes force. Besides, the formula for calculating the optimal helical angle of vortex tools was established according to the principle that the vertical resultant force on fluid droplets should be the maximum. And afterwards, each acting force was comprehensively analyzed in terms of its origin, characteristics and direction based on the established force analysis model. Magnitude comparison indicates that the forces with less effect can be neglected, including virtual mass force, Basset force and convection volume force. Moreover, the vertically upward centrifugal force component occurs on the fluid droplets in swirling flow field instead of those in the conventional flow field of wellbores, which is favorable for the fluid droplets to move upward. The reliability of optimal helical angle calculation formula was verified by means of case analysis. It is demonstrated that with the decrease of well depth, the fluid-carrying capability of gas and the optimal helical angle increase. The research results in this paper have a guiding significance to the optimization design of downhole vortex tools and the field application of downhole vortex drainage gas recovery technology.

The paper puts forth detailed optimization procedure for number of lobes of an innovative ‘Low Cost’ design of staircase climbing platform. Available designs[1] to [6] are not cost effective. Total new concept of specially designed wheels is put forth. The said configuration uses ‘Lobbed’ driving wheels with the shape of each lobe, conjugate with the profile of steps. There was an open choice to select number of lobes. Hence it was necessary to decide optimum number of lobes for the proposed design. Universal method of ‘Design of Experiments’ is used for the said optimization. Detailed force analysis at the point of contact between lobbed conjugate wheel and corresponding step profile is also carried out to decide optimum thickness of the wheels. Overall results are presented in last section.

The knuckle is difficult to form for their complex structures and great changes in cross sections during forging process. In this paper, by using of DEFORM simulation technology, analysis was made on forging force and energy in the main forging stages of typical truck knuckle. In addition, analysis has also been done on force and energy requirements and eccentric load requirements. The purpose is to select suitable press and provide design basis for establishing truck knuckle forging production line which is high efficient and stable. As a result, 8000T hot die forging press was selected to produce truck knuckles.

As a kind of biogas, landfill gas can be of high economic value after purification. Membrane separation is an energy-saving and environmentally benign gas purification technology easy to be assembled and rearranged with the advantage that it keeps stable performance while being scaled-up. To achieve high recovery and separation purity, a multi-stage membrane separation is usually designed to efficiently combine several membrane components. As the landfill gas composition and turnout vary a lot, an integrated design is to be conducted in such a way that the separation and purification cope with uncertain concentrations and flowrate. Furthermore, the best profit is to be achieved by considering both investments and operational costs. In this paper, three different strategies are proposed for landfill gas purification through the multi-stage membrane separation, including a sequential reference-structure-based strategy (SeqRS), a sequential superstructure-based strategy (SeqSS) and a simultaneous superstructure-based strategy (SimSS). The latter proves to provide the highest annual profit and the lowest computation costs. The results of comparison are further supported by the driving force analysis.

The attachment of bubbles onto a collecting surface plays a critical role in flotation which is utilised for the separation of mineral ores, coal or plastic materials. While mineral flotation deals with fine particles and larger bubbles, this work is focused on the opposite case of an interaction of a single rising bubble (Db

This study aims to investigate the effect of frother type and concentration on the detachment of galena particles during the coalescence of a bubble pair. An experimental technique was used that allows the interaction between two individual air bubbles and measurement of particles that leave the surface as a result of the merging process. Two different frother types, OrePrep® F-549 a mixture of polyglycols and methyl isobutyl carbinol (MIBC), were used in the study. The results showed that the presence of frothers has a significant effect on the number of hydrophobic particles detaching from the surface of the oscillating bubble. In general, it was found that there is a linear correlation between the percentage of particles leaving the surface and the frother concentration. The F-549 frother was found to be more effective compared to MIBC, as it provided more damping to the oscillating bubble. It was also observed that the presence of particles on the bubble significantly damped the oscillation, resulting in less adhering particles to drop off the bubble surface. A force analysis was conducted to establish a possible link between the detachment forces that arose from the bubble oscillation and frother concentration.

The design of a soft-recovery system is critical to a researcher's ability to analyze hypervelocity projectiles. The researcher may decide to use one method over another based on several criteria, including whether or not non-deformed projectile measurements are required. This report analyzes the forces two different soft-recovery methods impart on the projectiles collected. Method 1 utilized three polyethylene water barrels placed “end-to-end” horizontally, providing 2.6 meters (9 feet) of water to stop the projectile. Method 2 is a modification of the soft-recovery method utilized in “Soft-Recovery of Explosively Formed Penetrators” by Lambert and Pope [1] . This method utilizes a series of several materials with an increasing density gradient, placed end-to-end over 14.3 meters (47 feet) to stop the projectile. Despite the fact that explosively formed projectiles (EFPs) of the same design were fired into each recovery method, the projectiles collected using the two methods differed in shape, size, weight, and the number of pieces collected. Since the EFP designs were identical to begin with, the physical differences are most likely due to the different magnitudes of the forces exerted on the projectile during deceleration. Drag force calculations will be performed for both recovery methods in an attempt to determine the differences in the drag forces exerted on the projectile during its deceleration. The results of the calculations will assist in determining to what extent the physical deformation of the projectile is due to the material selection of each recovery method. The consistency of the shapes and weights of the recovered projectiles will also be briefly addressed to assist the researcher in choosing the most useful recovery method for a given objective.

RMG sector is one of the biggest and most GDP earning sectors in Bangladesh. This sector works with some raw materials. One of those raw materials is industrial sewing thread. RMG sector could be stopped without industrial sewing thread. There are many industries in the world for manufacturing sewing threads and accessories. The current research contains a brief study of sewing thread and accessories industry in Bangladesh. For completing this study researcher went through the porters five force analysis, swot analysis as well as positioning of the industry. Researcher has tried to analyze the real situation for finding solution of the study.

This study investigates the influence of ground water injection on the initial movement of non-cohesive sediment particles on a riverbank slope analytically and experimentally. By including the hydraulic gradient in the force analysis, the critical condition was derived to account for the effect of seepage flow, showing that the seepage hydraulic gradient and the riverbank slope are governing parameters in modifying the incipient motion of sediments on a riverbank slope. Experimental investigations were performed in an open-channel flume for various riverbank slopes and hydraulic gradients of injection, showing that the critical shear stress increases with decreasing riverbank slopes and vise-versa, while injection reduces the critical value. All experimental data agree well with the theoretical derived expression of the critical condition in the case of injection.

Bubble detachment diameter is one of the key parameters in the study of bubble dynamics and boiling heat transfer, and it is hard to be measured in a boiling system. In order to predict the bubble detachment diameter, a theoretical model is proposed based on forces analysis in this paper. All the forces acting on a bubble are taken into account to establish a model for different flow boiling configurations, including narrow and conventional channels, upward, downward and horizontal flows. A correlation of bubble contact circle diameter is adopted in this study, and it is found that the bubble contact circle diameter has significant effect on bubble detachment. A new correlation taking the bubble contact circle diameter into account for the evaluation of bubble growth force is proposed in this study, and it is found that the bubble growth force and surface tension force are more significant in narrow channel when comparing with that in conventional channel. A visual experiment was carried out in order to verify present model; and the experimental data from published literature are used also. A good agreement between predicted and measured results is achieved.

Atomic force microscopy (AFM) is a vital instrument in nanobiotechnology. In this study, we developed a method that enables AFM to simultaneously measure specific unbinding force and map the viral glycoprotein at the single virus particle level. The average diameter of virus particles from AFM images and the specificity between the viral surface antigen and antibody probe were integrated to design a three-stage method that sets the measuring area to a single virus particle before obtaining the force measurements, where the influenza virus was used as the object of measurements. Based on the purposed method and performed analysis, several findings can be derived from the results. The mean unbinding force of a single virus particle can be quantified, and no significant difference exists in this value among virus particles. Furthermore, the repeatability of the proposed method is demonstrated. The force mapping images reveal that the distributions of surface viral antigens recognized by antibody probe were dispersed on the whole surface of individual virus particles under the proposed method and experimental criteria; meanwhile, the binding probabilities are similar among particles. This approach can be easily applied to most AFM systems without specific components or configurations. These results help understand the force-based analysis at the single virus particle level, and therefore, can reinforce the capability of AFM to investigate a specific type of viral surface protein and its distributions.

Honing is a machining process that can economically produce very exact bores regarding form, geometry and surface quality. It is mainly used as the final finishing operation for ready made parts and typically conducted on the inner surface of a cylinder. Due to their specific surface structure which has a good ability to keep lubricants and a high wear resistance, honed parts usually serve as functional surfaces to guide moved parts. Today, the main fields for applications of honing technology can be found in most sectors of the metal working industry, e.g. the automotive industries, hydraulic and pneumatic manufacture and aircraft industries. During the long-stroke honing process the tool, equipped with one or several abrasive honing stones, is performing three overlaying movement components. These are a rotational movement, an oscillating stroke movement in axial direction and the radial feed movement of the honing stone. This feed movement is one of the decisive factors for the results of the honing process. It can be realized through feed control or, in a more recent approach, through force control strategies. By feed controlled honing, the position of the honing stone is changed in defined invariable steps in certain time intervals. In contrast, by force controlled honing the force of the honing stone against the wall of the workpiece is measured indirectly by a force sensor, which is located within the feed unit of the honing machine. A required force value is given and, if necessary, the honing stone is fed outwards to reach and maintain a constant cutting force throughout the honing process. This constant force is supposed to produce better results of the honing process in terms of geometric and form accuracy as well as surface structure. The presented research studies aim at improving process know-how to further increase the production accuracy and process repeatability. In a comparison between parts honed with the two different feeding strategies for the honing stone, force components and moments were analyzed and correlated to the phases of the process and several influencing parameters. In addition to the forces and moments measured during the honing process, the quality parameters of the honed parts have also been analyzed and compared.

The rivers and lakes are not only important parts of the wetland, but the main agricultural irrigation water and important freshwater resources. The changes of the rivers and lakes have heavy effect on the environment and economy. Taking Zhuhai City as the study area, selecting the rivers and lakes as research object, using the Landsat5 TM data in 1995, Landsat7 ETM + data in 2002, CBERS-02B CCD and HR data in 2009 as the main information source, this paper makes an remote sensing interpreation using the combined method of the supervised classification, non-supervised classification, man-computer interactive interpretation and rule-decision classification. Thus, the thematic information of the rivers and lakes are extracted at the three phases in Zhuhai City; then the spatial distribution pattern and dynamic change rules of the rivers and lakes in Zhuhai City are monitored; finally, the driving force of these changes are analyzed. The results show: the area of the rivers increased 6% from 1995 to 2009; but to the lakes, decreased 58%. The increase of the rivers area is because reclamation projects cause the big change of the sea-land position; whereas the decrease of the lakes area is due to the factors such as the warming climate and increasing populaiton.

This paper presents the theoretical details of the journal bearing design for Revolving Vane (RV) rotary type compressor. The mathematical models, force analysis, and the theoretical design analysis for the dynamically loaded journal bearing of the compressor are presented. The variations of the minimum oil film thickness and the maximum film pressure developed are shown and the influences of design parameters, compressor configurations, and operating conditions on the journal bearing performance are described. For an air-conditioning compressor of 1.5 kW cooling capacity, the lowest minimum oil film thickness for lower and upper journal bearings is 6.6 μm and 4.3 μm respectively, when the cylinder is simply supported and the rotor is cantilever-supported. The lowest minimum oil film thickness for the journal bearing, which supports the cylinder, reduces to 4.0 μm if the cantilever-type support is used. Besides that, a short-fat configuration of RV compressor is favorable in the interest of lowering bearing forces.