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To enhance the power-to-hydrogen (P2H) efficiency and multiple energy utilization efficiency of the hydrogen-electric integrated energy system (HE-IES), an optimal operation framework considering the P2H factor is proposed. First, the proton exchange membrane electrolytic cells model which considers mass transfer characteristics is established. Efficient hydrogen production operating parameters are obtained through simulation to maximize the P2H efficiency. Second, the HE-IES is established, including the hydrogen flow system, wind power (WP), energy storage systems, gas boiler, combined heat and power and methanation unit. Based on the characteristics of the devices and efficient hydrogen operating parameters, the optimal operation framework considering the P2H efficiency factor is proposed. To realize the low economic operating costs and maximize the utilization of WP, a multi-objective function based on fuzzy membership function solving is applied. Finally, the case studies show that the proposed operation framework reduces the economic operation cost by 28.29% and improves the WP utilization rate by 31.9%. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the L.N. Gumilyov Eurasian National University. Technical science & Technology series is the property of L.N. Gumilyov Eurasian National University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractSimilar to pile group, the process of designing an anchor group requires the determination of an efficiency factor that describes the overlapping effects of neighboring anchors. This research article introduces an efficiency factor denoted as ξ, which represents the ratio of the ultimate uplift pressure of a single anchor within a group to the ultimate uplift pressure of an isolated anchor. The primary approach employed involves advanced 3D finite element limit analysis with an adaptive meshing technique, which can be utilized to examine the uplift stability problem of 3D anchor groups. Numerical findings are compared with those obtained from previous research, incorporating both experimental and analytical results. This would ensure that our results are validated and provide valuable information into the performance of anchor groups. In addition to these findings, we introduce a MARS machine learning model, which has been trained using a dataset of 875 data points. This model is designed to establish an empirical equation that can be practically used for design purposes. To further enhance our understanding, we present the relative importance index (RII). This index allows us to identify which factors have the most significant impact on the behavior of anchor groups. In conclusion, the results presented in this article are of practical significance for the geotechnical engineering community. [ABSTRACT FROM AUTHOR]

AbstractA tri-hierarchical incomplete block (TriHIB) design is defined as an arrangement of v equi-replicated treatments in three levels of blocking such that each block of the first level contains m1 blocks of second level and that of second level contains m2 blocks of the third level. Every level of a TriHIB design, treated independently, is an incomplete block design (IBD) and ignoring any one level of blocking, results into a bi-hierarchical incomplete block (BiHIB) design. Here, two general methods of construction of TriHIB designs are proposed. In the first method, popular association schemes (viz., triangular, Latin square and rectangular) of partially balanced IBDs have been used for developing three series of designs with equal/unequal block sizes at higher levels of blocking. Second method yields another series of designs, through cyclic development of two initial sequences, with equal block sizes at first two levels and equal/unequal block sizes at the third level of blocking. A list of parameters of TriHIB designs for number of treatments up to 30 is presented, along with efficiency factors. Further, for easy accessibility and wider adaptability of these designs, an R package ‘Tri.Hierarchical.IBDs’ has been developed for the generation of the proposed designs. [ABSTRACT FROM AUTHOR]

Soil reinforcement is increasingly applied in many geotechnical applications due to its high performance and justified costs than other alternatives. Footings are frequently located close to each other leading to interference with one another's efficiency. Closely constructed shallow footings on geo-reinforced soils (GRS) have a markedly significant effect on bearing capacity (BC) combined with more complex interaction behaviors than individual footings requiring further research. This research aims to investigate in more detail than hitherto done with attention paid to the BC, tilt and efficiency factors of interfering footings. The potential BC failure and resistance mechanisms are discussed in detail. Optimal reinforcement variables and new relationships are proposed for various footing geometries using new dimensionless interference factors to achieve more accurate analysis and design of twin footings on GRS. Based on shortcomings of the cited studies, design guidelines and future research recommendations are made. Results reveal that maximum interference factors of the interacting footings on GRS appear when the ratio of the center-to-center distance of footings to a footing width Δ/B is almost 1.5–2 depending on the footing geometry, underlying soil and reinforcement characteristics. However, at the range of Δ/B = 3–5 the interference factors disappear. Optimizing reinforcement parameters, the combined influence of reinforcement and interference led to increasing the magnitude of BC by 1.35 to 3.6 times. Reinforcement below interfering footings reduces the depth of influenced stress significantly. [ABSTRACT FROM AUTHOR]

The question of the feasibility of increasing the energy efficiency of large chemical and oil refining industries by replacing furnace heaters of process heat carriers and raw materials with vapor compression heat pumps is considered. An analysis of the relationship between the technical configuration of vaporcompression heat pumps, the operating parameters of their operation (determining the value of the energy conversion coefficient) and the ratio of the cost of various energy carriers is carried out. The presented results of a comparative analysis of the energy efficiency of various options for replacing a furnace with a vapor compression heat pump reflect the decisive influence of the technical level and design configuration of a vapor compression heat pump on the choice of the preferred upgrade option. However, a significant difference in commercial energy prices significantly changes the preferred ranking of these options.

In practical scenarios, it is common to encounter adjacent reinforced concrete (RC) footings that have different loads and shapes near the top of a stabilized slope. The proximity of these footings, along with the reinforcement and slope characteristics, can influence the bearing pressure and failure mechanisms. Surprisingly, the existing literature has not adequately addressed the behavior of closely spaced non-identical footings with varying loads on reinforced soil. To fill this knowledge gap, our study focused on modeling two non-identical RC footings on both unreinforced and geocell-reinforced sand (GRS) slopes. These footings were subjected to different gravity loads from buildings of various sizes. For this purpose, a series of large-scale experiments and carefully selected relevant case studies involving sand were conducted. By considering optimal values for the embedment depth and geometry of geocell reinforcement, the combined effects of footing asymmetry, material properties, load intensity, and geocell reinforcement on the bearing pressure of the RC footings were investigated. The impact of the spacing ratio between footings and their distance from the edge of the slope on the overall performance and efficiency of the RC footing systems was also explored. Results were presented using non-dimensional efficiency factors and bearing capacity improvement parameters. Findings conclusively demonstrated that the inclusion of geocell reinforcement, combined with the interference effect between footings, significantly enhanced the load-carrying capacity of the non-identical RC footing systems on slope surfaces, resulting in a remarkable improvement exceeding 300%. Additionally, broader footings exhibited higher levels of efficiency and improvement, with variations based on the distance of the footings from the slope crest and the disparity in load intensity.

In recent years, zinc industry waste jarosite as a partial replacement of cement for high-strength concrete manufacturing has gained importance. Hence, the current study attempts to better understand the jarosite's efficiency in pavement quality concrete. Two different approaches based on compressive strength-to-water cementitious ratio relation and flexural strength-to-water cementitious ratio relation at different replacement levels of jarosite were considered to evaluate jarosite's efficiency in pavement quality concrete. It was observed that both the water-to-cementitious ratio and the dose of jarosite significantly affect the strength characteristics of the concrete. The results showed that the optimum quantity of water for the jarosite blended concrete could be achieved well by the difference in water-to-cementitious ratio (Δw) based efficiency factor concept considered in the study. Further, based on the achieved efficiency factors, it was found that the jarosite is more efficient in terms of flexural strength when compared to compressive strength. [ABSTRACT FROM AUTHOR]

The article is devoted to the investigation of reactive power compensation modes in a closed electrical network, which is significantly loaded with active-inductive elements in the nodes of electricity consumption. The initial mode without compensation is compared with the modes of partial and full compensation of reactive power using capacitor compensation banks. It is shown how to determine this mode using search optimization using a visual model of the electrical network. Quantitative indicators of the compared modes are presented, which convincingly demonstrate the advantages of full reactive power compensation in the electrical network. [ABSTRACT FROM AUTHOR]

One of the innovative directions of heat treatment of soil in the technologies of decontamination from pesticides, oil products and disinfection is heating in a microwave electromagnetic field. Numerical studies testify to the effectiveness of the microwave treatment method. This is due to the peculiarities of the interaction of the microwave field with dielectric materials. Unique effects arise, such as the possibility of local heating, volume heating of the material, unidirectionality of pressure and humidity gradients. This contributes to the intensification of transfer processes and the possibility of energy savings. However, the challenge at present is to determine the processing regimes, including load mass, specific microwave field power, electric field strength, material layer thickness, and processing time, under which the microwave method will be energy efficient. Conducting multifactorial experimental studies allows determining the conditions of energy feasibility of microwave soil treatment. Therefore, the object of research is the process of heating a dense layer of soil under the action of a microwave electromagnetic field. The results of studies on the effect of microwave treatment of soil contaminated with organophosphorus pesticides, contaminated with petroleum products, and under what conditions the qualitative effect was obtained, as well as the results of the effect of the microwave field on the pathogenic microflora of the soil used for growing plants, were considered. The high quality of implementation of soil treatment technologies is determined. Energy efficiency was determined on the basis of data on temperature and moisture content, analysis of thermograms of microwave heating of chernozem and clay soil, analysis of the influence of material layer thickness, influence of dielectric properties and power of the microwave field. According to the results of thermal calculations, the values of the efficiency of the microwave chamber and the intensity of the electric field were determined, which are recommended as the basis for scaling in order to transfer the experimental results to industrial installations. During the research, specific experimental methods of research under microwave heating conditions, analytical methods of thermal calculations, developed by the authors of the experimental research methodology were used. Experimental studies were carried out on the installation created by the authors. The results of the research are intended for the wide implementation into practice of technological calculations of microwave chambers for heat treatment of soils, intensification of disinfection processes under the conditions of energy efficiency of the transformation of the energy of the microwave field into the internal energy of the soil. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power is the property of Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. Developing and adapting domestic technologies aimed at the maintenance and repair of foreign equipment is impossible without design documentation. The object of the study was the volumetric hydraulic drive Sauer-Danfoss of 90 series consisting of a hydraulic pump 90R100 and a hydraulic motor 90M100. The purpose of the study is to determine the nominal dimensions and permissible variations in dimensions of critical parts that affect efficiency of the foreign hydraulic drive. Materials and Methods. The first series of bench tests was devoted to finding the ranges of variation of significant factors influencing the volumetric efficiency. In the second series, there were constructed regression models and by using the steepest ascend method, there were determined the values of critical parts wear and clearances in the critical parts connections affecting efficiency of the hydraulic drive Sauer-Danfoss. The nominal values of dimensions and permissible variations in dimensions of the hydraulic drive critical parts were determined by the dimensional analysis method. Results. The bench tests made it possible to determine the ranges of changes in critical parts wear and clearances in the critical parts connections of volumetric hydraulic drives that affect the volumetric efficiency. There has been proposed and implemented a comprehensive approach to determining the nominal dimensions and permissible variations in dimensions of critical parts of foreign equipment units. This approach suggests a combination of experimental studies (bench tests) and the method of dimensional analysis. For the new volumetric hydraulic drive Sauer-Danfoss series 90 the following values are received: diameter of a hole in the cylinder block under the piston 22,7+0,006 mm, piston diameter 22,7–0,004 mm, diameter of a hole in the rear cover under the spool 9,5+0,004 mm, spool diameter 9,5–0,0025 mm. Discussion and Conclusion. There have been determined the nominal values of dimensions, permissible variations in dimensions of critical parts, and the values of technological clearances in the critical parts connections of the new volumetric hydraulic drive Sauer-Danfoss series 90 that affect its efficiency. The results obtained are the basis for the development of technology to restore the efficiency and increase the durability of the volumetric hydraulic drive units of foreign origin.

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main aim of this study is proposing the best solution to the bearing capacity of two adjacent footings on rock masses depending on the spacing between them. Upper bound method of limit analysis was employed to develop the bearing capacity formulation. Two failure mechanisms were considered for the bearing capacity of rock masses subjected to the loads of two adjacent footings. The nonlinear Hoek–Brown failure criterion was used to simulate the rock mass behavior. The effect of adjacency of footings on the bearing capacity was considered using a coefficient called the efficiency factor. The applicability range of each of the two considered mechanisms was verified for a wide range of rock mass properties. Finally, a criterion was proposed for choosing the most suitable failure mechanism and the corresponding bearing capacity of rock masses. According to the results, within the small distance between the two footings, the footings and the rock mass between them move downward. In such a mode, the bearing capacity of the rock masses increases with increasing the spacing between the two footings. When the spacing becomes larger than a particular value, a decreasing trend occurs in the bearing capacity, and the rock mass between the two footings moves upward. The results show that considering 19 triangular wedges in the failure mechanism is enough for obtaining appropriate magnitude of bearing capacity. In addition, adjacency of footings may increase the bearing capacity up to 63% with respect to an isolated single footing. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Processes of drying a dense layer of grain crops, such as wheat, barley, oats, buckwheat under microwave heating are studied in the article. In order to substantiate the choice of the microwave energy supply method, continuous and intermittent (oscillating) supply was studied under the same conditions. A description of the experimental setup is provided, which allows conducting research on the heating of bulk materials during microwave, microwave-convective, and convective drying. The method of evaluating the thermal efficiency of a microwave chamber is presented. A change in the course of the dependence of the efficiency on the loading mass and the exit to the limit value, after which the increase in mass does not affect the efficiency, have been established. The results of the study of temperature and moisture content during drying of grain materials in a microwave field are given. The dependences of average integrated moisture contents and grain temperatures on time at different sample weights were obtained. With an increase in mass, the duration of the process with the same moisture removal increases, and the temperature of the material decreases. It is shown that during microwave heating there are periods of warm-up, constant and falling drying rates, which are also characteristic of other methods of heating. Based on the data on temperature distribution and moisture content in three- and four-layer samples, the attenuation coefficient of microwave energy in the layer was calculated. Significant nonuniformity of moisture content and temperatures along the thickness of the sample in the conditions of the moisture-proof base of the experimental cell is shown. The results of comparison of drying speed, specific energy consumption and final temperatures of layer with microwave and pulsating microwave energy supply are given. Based on the data on temperature distribution and moisture content in three- and fourlayer samples, the attenuation coefficient of microwave energy in the layer was calculated. [ABSTRACT FROM AUTHOR]

The use of photosensitive proteins has become a competitive solar energy solution, owing to its pollution-free nature, high conversion efficiency, and good biocompatibility. Bacteriorhodopsin (bR) is an important light-sensitive protein that is widely used in the fabrication of photoelectronic devices. However, research on the optimization and comparison of the immobilization techniques is lacking. In this study, in order to obtain bR films with a high energy conversion efficiency, three immobilization techniques, namely dropcasting, electrophoretic sedimentation, and Langmuir–Blodgett deposition, were used to fabricate films, and their topographical and photoelectrical characteristics were compared. All three immobilization techniques can transfer bR molecules to substrates, forming functional photosensitive bR films. The absorption of the bR films at 568 nm reached the highest value of 0.3 under the EPS technique. The peak photocurrent for the EPS technique reached 5.03 nA. In addition, the EPS technique has the highest efficiency factor of 13.46, indicating that it can generate the highest value of photocurrent under the same light conditions, owing to the improved orientation, and no significant decrease in the peak photocurrent was observed after three weeks, which indicates the stability of the photoelectric response. These results indicate that the EPS technique has a great potential for the photoelectrical device fabrication and solar-energy conversion. [ABSTRACT FROM AUTHOR]

Introduction. The widespread use of telelearning raises the issue of ensuring its effectiveness. Researchers consider various factors, but student readiness for such learning has not yet become the subject of systemic research in domestic science. The objectives of the article are: to reveal personality predictors of online learning success, to identify the components of student readiness for such learning (on the basis of foreign works); to characterize the readiness and self-efficacy of students’ online educational activities drawing on empirical data. Materials and Methods The researchers utilized the methods of theoretical analysis of the problem and the survey method. The author’s questionnaire was used to collect the data on the online activity of the students, self-assessment of readiness and effectiveness of online learning. 252 first- and second-year IT-students participated in the survey. Results. Five components of students’ readiness for online learning have been identified: attitude towards online learning, self-directed learning, time management, communicative competence, and technical competence. The students’ attitudes towards online learning are ambivalent. The students understand the importance of such training, but they are not willing to invest enough time and effort into it. Two interrelated components (self-directed learning and time management) contribute most to the overall online learning readiness. Online learning self-efficacy is related to technical competence and attitudes towards online learning. Discussion and Conclusion. The results will be useful for further research of the factors and ways improving online learning effectiveness. The research prospects are the development of psychodiagnostic tools for assessing the online learning experience and readiness of students and the diversification of the sampling by adding students from different programme tracks and with different experiences in online educational activities.

Bookkeeper, the most widely used deacidification process based on MgO particles, was systematically evaluated on two sets of nonvaluable historical paper samples. Established analytical methods, such as pH and alkaline reserve determination, were used, as well as SEM EDS analyses to evaluate the distribution of Mg-rich particles on the paper surface and in the cross-section of the paper. The degradation rate constants of untreated and deacidified paper samples after accelerated thermal degradation were calculated based on weight average molecular mass determination to evaluate the lifetime extension of paper. The efficiency factors determined after accelerated thermal degradation of untreated and treated paper showed that paper lifetime prolongation after Bookkeeper deacidification treatment is highly limited for most of the investigated paper samples. No correlation was found between the alkaline reserve content or the pH and the degradation rate constants of the deacidified paper samples, but the paper degradation rate correlated with the paper samples pH before deacidification treatment. SEM EDS analysis showed that Mg-rich particles remained on the paper surface, which explains the limited effectiveness of the treatment. [ABSTRACT FROM AUTHOR]

This article presents the results of studies comparing the mix sintering process in a bed loosened with vertical rippers and a dense bed of a mix. In this study, for the first time, it was established that mix sintering in a loosened bed with a maximum height of 700 mm is more efficient in terms of sintering speed than that in dense beds of lower heights (up to 550 mm), without deteriorating the quality of the sinter cake. The results confirm that in a loosened bed, the vertical sintering rate of the mix increases as its height increases. This article discusses relevant problems associated with the operation of the ignition hearth, throttling of wind boxes, and energy-consuming operation of exhausters. [ABSTRACT FROM AUTHOR]

Due to a high solar energy utilizing efficiency, Direct-expansion Solar-Assisted Heat Pump (DX SAHP) system has been a research hotspot for many years, especially for the system using PV/T module as the evaporator. The heat transfer throughout the PVT evaporator is an important factor for either electrical or thermal performance. We have developed and analyzed numerically the temperature distribution of a multi-source PVT heat exchanger of serpentine shape to fit a function as evaporator/condenser for Direct-expansion Photovoltaic/Thermal-Heat Pump (DX PVTHP) system. The suitability of the developed model was based on the calculated results of the efficiency factor and simulated results of temperatures of heat exchanger and working fluid as well the working fluid pressure drop. During the numerical simulations, we have considered different temperature influencing factors such as the refrigerant and refrigerant flow rate, spacing between the adjacent tubes of the heat exchanger, backside convection and radiation effect and finned heat exchanger. Simulated results showed that the serpentine PVT heat exchanger with fins and small space between tubes (62.5 mm) at 0.02 kg/s flow rate could achieve better results in terms of uniform temperature distribution, smaller fluid pressure drop (0.078 bar) and the highest efficiency factor (0.9873) which make it recommended as the best option for suitable evaporator/condenser. The average PV temperature reached by cooled and uncooled PVT evaporator at 0.02 kg/s flow rate was 47.81 °C and 71.11 °C, respectively. It was 40.99 °C and 37.07 °C at the flow rate of 0.035 kg/s and 0.05 kg/s, respectively, and 44.44 °C for PVT evaporator with smaller space between tubes at 0.02 kg/s. The average PV temperature reached by the PVT evaporator with fins was 40.734 °C at the flow rate of 0.02 kg/s while it was 53.956 °C when the unit is insulated. [ABSTRACT FROM AUTHOR]

Mine transport is an integral part of mining process. The performed analysis of modern monorail autonomous locomotives indicates that this type of underground auxiliary transport is the most promising today due to a number of advantages that were identified in this study. To assess performance indicators of mine monorail locomotives, a number of characteristics are currently used, for instance, the dependences between several parameters of propulsion system operation. The type of characteristic is determined by an independent variable to be selected from the list of the operational or design parameters. To substantiate performance indicators of autonomous mine suspended monorail locomotives, the authors proposed the relationship between the characteristics of the traction energy chain equipment and the diesel locomotive propulsion system efficiency factor. To assess the efficiency of mine suspended monorail locomotive operation, a composite indicator for assessing efficiency of various types of traction was proposed: the operational efficiency factor. This indicator takes into account varying the efficiency factor of the energy chain units depending on their operating modes. When determining the functional dependencies of varying the efficiency factor of power and auxiliary units of monorail locomotives, a grouping of the main parameters according to the features depending on the economic characteristics of the propulsion system and its operating modes was proposed. The operational efficiency factor of the locomotive as a whole is determined both by the economic characteristics of all units of its energy chain and by the modes of their operation.

Background. The transformer is a static electromagnetic apparatus designed to convert an alternating current of one voltage into an alternating current of another voltage of the same frequency. The transformer performs AC voltage conversion and/or galvanic isolation in various applications – electric power, electronics and radio engineering. The transformer has at least two windings, which have a common magnetic conductor and which are electrically isolated from each other. Materials and methods. The development of the scheme given in this article is based on the theory of an active bipolar – a part of an electric circuit isolated relative to two terminals containing an energy source (or compensated sources) and a passive four-pole – a part of the circuit that has two pairs of terminals and does not contain energy sources. A transformer can act as a typical active bipolar, as well as a transformer can act as a passive four-pole. Results.The article presents the development of optimization of transformer substitution schemes, which are convenient for theoretical analysis and in calculation practice. If the question arises – why the specified circuits are effective, then the next answer will follow – since they allow you to obtain the desired ratios of the circuits of the primary and secondary windings easier, faster and allow you not to distort such a parameter as accuracy. Conclusions. Moreover, the logical structure of these relations is so expressive in essence, that it is possible to correct known criteria, as well as the wording of new ones. Consequently, the schemes mentioned in this article will be of interest in production and design developments, as well as in the teaching and methodological plan.

Comparative estimation of energy parameters of power amplifiers of single-band radio transmitters using automatic mode adjustment using a deterministic two-frequency test signal instead of a random single-band signal modulated by speech is investigated in the work. Relationships are found that allow judging the power consumption of the terminal stage of the power amplifier with automatic mode adjustment under various types of modulation based on the results of measurements obtained during tests. The ratios between the power consumption of the output stage when amplifying the random speech signal and amplifying the deterministic two-frequency test signal are obtained both without taking into account losses in the controlled power supply and taking into account such losses. Method is proposed for calculation of energy gain and efficiency factor (efficiency) when applying automatic control of supply voltage of output cascades of shortwave transmitters intended for modulation with speech signals. The loss in the regulated power supply has been estimated. The advantage of power amplifier circuits with automatic mode adjustment is justified.

Previous studies on concrete have identified silica fume (SF) as the most effective supplementary material, whereas fly ash (FA) and slag have been identified as economical materials with long term strength potential. Development of blended cement mortar referred to as blended mortar (BM) requires similar assessment. The present study explores the application of Alccofine (AL) as supplementary material and compares its performance with conventional materials namely SF, FA and ground granulated blast furnace slag (GGBS). The mortar specimens with binder to fine-aggregates (b/f) ratio of 1:2 are prepared at water to binder (w/b) ratios of 0.4 and 0.35. The strength values and stress-strain curve for control and BM specimens are obtained at 7, 28, 56, and 90 d curing periods. The assessment based on strength activity index, k-value method and strength estimation model confirms that AL, despite lower pozzolanic activity, contributes to strength gain, due to reduced dilution effect. Assessment of stress-strain curves suggests that the effect of w/b ratio is more dominant on the elastic modulus of BM specimens than on control specimens. The observations from the study identify enhanced strength gain, improved elastic modulus and higher energy absorption as key contributions of AL making it a potential supplementary material. [ABSTRACT FROM AUTHOR]

The problem of determining the optimal ratios between the magnetic-conductor dimensions of a plunger electromagnet with an open-ended axial channel used in the drive of an impact machine is considered. The influence of the sizes of the open-ended axial channel on the existing range of extreme ratios of the main dimensions of the magnetic circuit based on the economy of active materials is established by the finite element modeling of the magnetic field. The criterion of the Q-factor equal to the ratio of the mass of the occupied volume of active materials to the useful mechanical work of the plunger electromagnet is adopted as the basis of economy. The dependence between the main dimensions of the magnetic core and the dimensions of the open-ended axial channel is determined. [ABSTRACT FROM AUTHOR]

Torsion in structural concrete members is a discipline where in-depth research is still possible and desirable. Sophisticated computer programs have been developed that deliver the ultimate load-bearing capacities after following the whole loading/deformation process. This paper presents the model of the characteristic failure cross sections (MCFC) and the efficiency factor, ?, of the skew reinforcement and applies them to fundamental test series from the literature on beams with rectangular cross sections loaded in pure torsion. A simple design formula is proposed and validated on test results from the literature. Failure modes and the influence of concrete strength are discussed. Minimum and maximum rates of reinforcement are defined, and detailing recommendations are given. [ABSTRACT FROM AUTHOR]

This work presents green lightweight reactive powder concrete (GLRPC) as a novel lightweight composite with improved properties by incorporating modified expanded polystyrene beads (MEPS) into green reactive powder concrete (RPC). It provides the advantages of both RPC and lightweight concrete (LWC). Because incorporation of the conventional expanded polystyrene (EPS) beads into the concrete mix results in a considerable loss of mechanical properties, it is necessary to find effective methods to preserve RPC properties as much as possible. The present work is devoted to the thermal modification of EPS. Various mixtures with different replacement levels of total RPC binder paste volume (0%, 15%, 30%, and 45%) with MEPS under different curing conditions (both standard water curing and heat curing conditions) were investigated in terms of their physical and mechanical properties. The results of the experimental study showed that MEPS beads had appropriate distribution into the GLRPC matrix without any considerable segregation. Replacement levels up to 30% of RPC paste volume by MEPS beads result in the development of high-strength lightweight concrete. Further replacement levels lead to lightweight concretes that drop into structural class. The water absorption shows a stronger dependency to curing temperature than replacement level of RPC paste volume with MEPS. The value of water absorption for all the studied mixtures, however, remained less than 2% that is relatively small. The microstructure analysis showed a very dense and uniform interfacial transition zone microstructure (ITZ) with good bonding of cement paste to MEPS beads. The relatively higher compressive strength of GLRPC cured at 200°C could be attributed not only to the development of a denser microstructure, but also to the development of hollow spherical polystyrene beads with hard and stiff shells resulting in an innovative high-tech plastic/cement-paste bonding. [ABSTRACT FROM AUTHOR]

So far rather large number of torches for chamber combustion of gaseous fuel differing among themselves on the nature of gas-distribution for mixture of fuel with air is known. For domestic oil-gas torches of power coppers their unification as combustion of fuels is characteristic, that is heat of combustion of the burned fuel can change in quite wide limits. Moreover, directly in use on thermal power plant their reconstruction is made for reduction of length of a torch, achievement of uniform radiation of a torch, change of local values of temperatures of a torch or reduction of their maximum values. As a rule, the detailed researches received after reconstruction of these torches are not conducted. Foreign torches are designed and made on combustion of fuel of a concrete type with the set heat of combustion. At the same time the main role for increase in efficiency is assigned to computer regulation of a ratio of fuel and air, gas-distribution - central tubular. Except high cost, the difficulty of application of foreign torches for domestic power coppers is connected with adaptation of automatic equipment of these torches to the system of automation of domestic coppers. Therefore for domestic coppers one of the directions them modernization for the purpose of increase in efficiency is reconstruction of schemes of gas-distribution in the existing torches. In this article the efficiency of application of peripheral tubular gas-distribution in comparison with the combined peripheral tubular gas-distribution combined with conic central gas-distribution when using as the main tagentsialny peripheral twist of air is investigated. These schemes of gas-distribution are applied in coppers of TGM-84A of the Kazan TES-3 and the Nizhnekamsk TES-1 on which experiments on identification of efficiency of these types of gas-distribution for combustion of natural gas of the Urengoy field are made.

At the stage at which agricultural gantry systems are being designed, developed, and studied, the question of a rational choice of tyres for such systems is relevant, as tyres are the most important part of an agricultural gantry system and have a significant effect on most of its operating properties. The methods that can be used for choosing tyres for traditional mobile-powered equipment are already well established by scientific experience, but the movement of agricultural gantry systems in permanent artificial tracks creates somewhat different conditions and demands for a pneumatic tyre when compared to a traditional tractor moving along agricultural soil. This is why the development of methods that will assist in finding rational parameters for the pneumatic tyres of agricultural gantry systems that are moving along compacted soil in permanent artificial tracks is an urgent and relevant task. The purpose of the study is to optimise the parameters for the tyres of agricultural gantry systems in terms of their being able to travel on compacted soil in permanent artificial tracks. Theoretical studies and the synthesis of the parameters for a pneumatic wheel to work with an agricultural gantry system took place by modelling on a PC the performance conditions of such a vehicle. The basis for the study methods was formed by the fundamentals of tractor theory and theoretical mechanics, using the software program Mathcad. The traction factor of an agricultural gantry system's pneumatic wheel was used as the performance criterion for the effectiveness of the work being done by the wheel. The physical object of study was an agricultural system that has been developed by us. As a result of the study, it was determined that the solving of the task that has been set out - using an analysis of partial derivates of the function of the efficiency of an agricultural gantry system's wheel – makes it possible to quickly and effectively determine the rational optimum points for its pneumatic tyre's parameters. It was determined that, for the agricultural gantry system at hand, and in view of the maximum efficiency of its pneumatic wheel, the wheel's tyre width must be within the range of 0.20–0.30 m and its diameter must be within the range of 0.90–1.25 m. With those ranges, it is recommended that the tyre's inflation pressure be increased from 100 kPa to 160 kPa because the partial derivates of the function of the efficiency at those parameters would decrease to near zero. It has been proven that the choice of tyre type for agricultural gantry systems should be based first on the choice of its width and then its load-bearing capacity – its diameter. The proposed methods for finding rational parameters for pneumatic wheels make it possible to determine the tyre parameters for all kinds of agricultural gantry systems which will be required to travel on compacted soil in permanent artificial tracks. For the agricultural gantry system that has been developed by us, using tyres of the 9.5R32 type provides the highest levels of efficiency, i.e. at a factor of 0.86.

The use of photosensitive proteins has become a competitive solar energy solution, owing to its pollution-free nature, high conversion efficiency, and good biocompatibility. Bacteriorhodopsin (bR) is an important light-sensitive protein that is widely used in the fabrication of photoelectronic devices. However, research on the optimization and comparison of the immobilization techniques is lacking. In this study, in order to obtain bR films with a high energy conversion efficiency, three immobilization techniques, namely dropcasting, electrophoretic sedimentation, and Langmuir–Blodgett deposition, were used to fabricate films, and their topographical and photoelectrical characteristics were compared. All three immobilization techniques can transfer bR molecules to substrates, forming functional photosensitive bR films. The absorption of the bR films at 568 nm reached the highest value of 0.3 under the EPS technique. The peak photocurrent for the EPS technique reached 5.03 nA. In addition, the EPS technique has the highest efficiency factor of 13.46, indicating that it can generate the highest value of photocurrent under the same light conditions, owing to the improved orientation, and no significant decrease in the peak photocurrent was observed after three weeks, which indicates the stability of the photoelectric response. These results indicate that the EPS technique has a great potential for the photoelectrical device fabrication and solar-energy conversion.

Carbon fibre-reinforced polymer (CFRP) was introduced over three decades ago to the field of structural engineering. The goal of this study is to investigate the effects of different types of sands and CFRP on the interface properties of sand and CFRP using the direct shear test (DST). Various type of soils including poorly graded sand (SP), silty sand (SM) and Ottawa sand (OTS) with different moisture conditions (dry and saturate) were considered. To increase the surface roughness, a layer of sand was placed on saturated carbon fibre during the curing period (SPSCFRP) and the normal stress was applied to it. Additionally, the effect of the fibre orientation and the normal stresses on CFRP-sand during the curing time was investigated. Based on the results, the interface behaviour between sand and CFRP depended on surface roughness, fibre orientation, the normal stress level and moisture condition. The results indicated that a reduction in moisture content caused an increase in the interface friction angle of specimens. Moreover, interface behaviour between CFRP-sand compared with interface behaviour between SPSCFRP and sand. Dissipated energy values obtained from DST. Results revealed that the dissipated energy under dry condition was higher than the saturated one. [ABSTRACT FROM AUTHOR]

Within the scope of this ex vivo study, the cut efficiency was investigated with eight diode laser wavelengths in the range from 400 to 1500 nm. Incisions on porcine gingiva samples were generated in CW-mode at a power range of 0.5–4 W using a bare fiber (∅ = 320 μm) in contact and non-contact mode at a cut speed of 2 mm/s. Cut depths, cut widths, and thermal damages were recorded based on histological sections and were evaluated via measurement masks. Moreover, with respect to the controllability of a therapeutic measure, an efficiency factor was defined. At powers above 2 W, for 445 nm, the maximum cut depth was 820 μm and 344 μm for 810 nm, respectively. At all wavelength and power ranges, the cut width averaged 125 μm. At minimum output power (0.5 W), the spatial expansion of the thermal damage in the tissue surface layer corresponds in the blue/green wavelength range from the very beginning of the laser impact to the fiber core diameter. It could be shown that increases in the diode laser power output do not correlate to the same extent with the incision depth nor with thermal damage to tissue. [ABSTRACT FROM AUTHOR]

It is widely accepted that concrete columns confined with fiber-reinforced polymer (FRP) jackets exhibit significant increases in strength and ductility with reference to the unconfined case. Existing experimental studies have indicated that the hoop rupture strains measured in the FRP jackets are significantly lower than the material strain capacity determined by the flat coupon tensile tests. An FRP efficiency factor is then usually used to define the ratio of the average hoop rupture strain to the material strain capacity of the FRP jackets, which governs the lateral FRP confinement as well as the peak strength and ultimate strain of the FRP-confined concrete under axial compression. FRP jackets are also expected to be a promising solution to repair damaged RC columns after fire exposure. However, there is lacking research on the behavior of FRP-confined fire or heat-damaged concrete columns. In particular, the FRP efficiency factor of FRP-confined fire or heat-damaged concrete columns has not yet been established. The study presents the results of an experimental study aimed to investigate the effects of the historical high temperature and the layer of basalt FRP (BFRP) jackets on the efficiency factor of BFRP for the confined heat-damaged concrete cylinders. A sum of 51 standard concrete cylinders is prepared and tested under axial compression. The parameters varied between tests are the historical high temperature (200°C, 400°C, 600°C, or 800°C) that is used to produce the heat damage of concrete cylinders and the number of layers of BFRP jackets (2, 3, or 4). The test results have indicated that the efficiency factor of BFRP jackets increases with the historical high temperature but decreases slightly with the increase in the BFRP layers. A new temperature-dependent design equation for the BFRP efficiency factor of the confined heat-damaged concrete is proposed to consider the effects of the parameters mentioned above and can be used for practical design.

This work deals with determination of thermal efficiency of spherical ball roughened collector aligned inclined to flow direction. Roughened collector produces more heat transfer compared to smooth ones but heat transfer augmentation comes at the cost of increased frictional losses. Lesser thermal efficiency of solar air heater has necessitated researchers to focus on its improvement by providing artificial flow modification techniques in the flow field. Laminar sublayer beneath the absorber plate will get disturbed and this helps to increase turbulence level of air. Present work discusses the influence of inclined spherical ball shaped roughness element and improving its thermal performance. Design considerations, geometries used viz. relative roughness pitch 9–18, relative roughness height 0.024–0.040, height-diameter ratio 0.5–2, angle of attack 35°-75°, flow conditions and their influence on turbulence viz. Reynolds no 2500–18500, heat transfer rate, absorber temperature and thermal performance enhancement factor have been thoroughly discussed. Finally concluding remarks and future scope for additional enhancement in performance of solar air heater is proposed. Maximum thermal efficiency for roughened ducts was found as 81% compared to 38% for smooth duct at parameters viz. 'relative roughness pitch = 12, 'relative roughness height' = 0.036, 'height-diameter ratio' = 1 and 'angle of attack' = 55֠ at mass flow rate = 0.0319 kg/s. • A novel type inclined spherical ball roughened duct is investigated experimentally. • Thermal efficiency is determined for different roughness configuration. • Variation in thermal efficiency with temperature rise parameter is presented. • Optimized value of flow and roughness parameter was determined. • Efficiency factor and heat removal factor is determined and discussed. [ABSTRACT FROM AUTHOR]

Introduction. The existing methods of assessing the technical condition of power hydraulic cylinders do not allow one to conclude about the need to restore worn surfaces of parts. The data on limit values of wear of parts (wear and tear value at which a decision is made to repair) in technical requirements to overhaul and other technical documentation of hydraulic cylinders are not currently available. The aim of the study is to determine limit values of wear of working surfaces of hydraulic cylinder parts of C series. Materials and Methods.To assess the technical condition of hydraulic cylinders used, the authors developed a device on the basis of the stand KI-28097M-GOSNITI, equipped with an independent hydraulic station and load hydraulic cylinder, at which bench tests were carried out in the operation of С series hydraulic cylinders to determine overall efficiency values. Results. Results of bench and micrometer tests of the former hydraulic cylinders of the С series (С75/30, С90/30, С100/40) are presented. The regression model of the relationship between total efficiency of C series hydraulic cylinders (С75/30, С90/30, С100/40) and wear of working surfaces of parts was obtained. According to this regression model obtained using the method of steep ascent, limit values of wear of the working surfaces of C series hydraulic cylinder parts (С75/30, С90/30, С100/40) were determined. Discussion and Conclusion. 19,5 % of hydraulic cylinders of С series (С75/30, С90/30, С100/40) were operated in an out-of-limit condition. In case of technical service companies carrying out the input control of to-be-repaired hydraulic cylinders, limit values of wear for hydraulic cylinder surfaces, determined by the method of steep ascent, allow for making proper decisions on the need of their restoration.

The article proposes to evaluate the efficiency of an autonomous vehicle, taking into account not only the energy consumption for motion, but also the time of motion, i. e. both factors — efficiency and performance — should be taken into account. As a criterion for evaluating the efficiency of vehicles, authors propose the multiplication of efficiency on performance — the energy efficiency indicator (EEI). The best will be the vehicle with the highest EEI. The indicator should be calculated according to the specified technical characteristics of the vehicle laid down in the technical specifications. This criterion is suitable both for the evaluation of the vehicle during the design and during operation. At the same time, it is possible to evaluate and compare the EEI of technical vehicles not only of railway transport. The article presents the criterion values for water, rail and air transport. Proposed criterion makes it possible to evaluate the change in vehicle efficiency over time due to technical progress. Since 1953, the energy efficiency of a diesel locomotive has increased almost 3 times. To calculate the operational energy efficiency, it is necessary to obtain data on the actual performance of the vehicle. On railway transport, this is data on train work in t·km, speed and fuel consumption. The EEI assessment based on operating data will show how correctly the organization of vehicle operation is built, how non-stationary modes of the power plant and specific modes of traction influence the overall performance of the vehicle, how well the vehicle is selected for these operating conditions.

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thermal conditions of adsorptive heat storage device operating in open-mode were considered when discharged. The main operating parameters affecting the final temperature of airflow which supplied to ventilated premises are determined on the example of heat storage device based on composite ‘silica gel – sodium sulphate’. The main factors which determine a final airflow temperature are confirmed to be initial values of temperature, absolute humidity and speed of airflow which fanned to the adsorbent layer. Algorithm of calculating the operational parameters of adsorptive heat storage device has been further developed. Proposed algorithm involves calculation of diffusion coefficient, mass transfer coefficient, final absolute humidity of airflow, volume of air which passed through adsorbent layer, adsorption, specific adsorption heat and final airflow temperature, then useful heat, heat inputs for operating heat storage device and its efficiency factor are estimated. The adequacy of the proposed algorithm has been confirmed according with experimental data for operating of open mode adsorptive heat storage device. Curves final temperature of in flowing air vs. time of discharge of heat storage device are stated to depend on characteristics of airflow which fanned to the adsorbent layer such as temperature, speed and initial absolute humidity. When these parameters increased, time to achieve plateau, i.e. maximal values of final in flowing air temperature decrease. The dependence of initial values of temperature, absolute humidity, speed of humid airflow and final airflow temperature is shown. Maximal temperatures of at most 65 – 80 ºC are stated at the initial temperatures and absolute humidity of initial airflow within the ranges of 20 – 30 ºC and 0.03 – 0.04 kg/m3, respectively. The results of the present study can be used for the development of energy-efficient systems and devices for air-conditioning in habitual inner space and warehouses. [ABSTRACT FROM AUTHOR]

Supercritical water fluidized bed is a novel gasification reactor which can achieve efficient and clean utilization of coal. The rough surface of particle produced during grinding and thermochemical conversion processing will deeply affect supercritical water-particle two-phase flow and heat transfer characteristics. In this paper, fully resolved numerical simulation of supercritical water flow past single rough sphere particle with the Reynolds number ranging from 10 to 200 was carried out to investigate the effect of surface roughness. The simulation results show that as roughness increases, the separation bubbles generated in the dimple enhance the flow separation but has no significant effect on the drag coefficient. Particle surface-average Nusselt number decreases with an increase of roughness and surface enlargement coefficient due to the isolation effect at low Re and local separation bubbles in the dimple at high Re. Furthermore, the effect of surface enlargement coefficient on heat transfer efficiency factor for supercritical water near the critical point is greater than that under constant property condition and has a higher dependence on Re. [ABSTRACT FROM AUTHOR]

An efficient maintenance allows extension of operating life of system, thus contributing to increase system performance. Computer systems like other systems must operate without interruption and applied strategies of maintenance must be efficiency. This paper proposes to define a maintenance strategy of computer system subjected both to corrective and preventive maintenance. These aspects are modelled by competing risks concept and the Alert-delay model, which are generally used in industrial systems. The approach is applied on real data from computer system, localized in an industrial company and different scenarios are generated following various maintenance strategies. These policies are evaluated through minimal, perfect and imperfect models of maintenance for corrective and preventive maintenance. Simulation results give failure intensity assessment and efficiency factor value. Final outcomes are validated by dependability measures to select best strategies of maintenance.

Numerical modeling is important for exploring the fundamental processes occurring in rock and for evaluating the real performance of structures built on and in rock mass system, and thus for supporting the design of rock engineering problems. Estimating the stability of rock mass foundation systems entirely based on a theoretical approach is a complicated task if there exists overlapping of their potential collapse modes. This paper applies finite element limit analysis to evaluate the bearing capacity of equally spaced multiple strip footings resting on rock mass obeying the modified non-linear Hoek–Brown failure criterion. Numerical solutions are expressed in terms of the efficiency factor that is dependent on the spacing between footings, as well as the rock mass properties. In addition, the effects of surface surcharge and footing roughness are quantified. The maximum spacing at which the interfering effect of adjacent footings becomes disappeared is evaluated and an algebraic expression for approximating the maximum spacing is proposed. Failure mechanisms for a few cases of rock mass under multiple strip footings are examined.