三相交流电磁铁的吸力分析

对三相交流电磁铁吸力进行了具体分析、比较,发现三相交流电磁铁中采用两个电磁线圈后对电路的失压保护作用更大,并给出两线圈端点连接的最佳方式.

DS7型直流快速断路器合闸电磁铁吸力分析

一、概述DZ7型直流快速断路器合闸电磁铁是螺管式的,其结构如附图所示.涉及到计算用的数据,经过实际测量标记在附图中.该断路器在使用说明书中规定,触头压力必须在350N以上.我们在现场发现,当触头压力在350N时,多数断路器合闸不上,因此引起我们对合闸电磁铁吸力进行核算.

吸盘式电磁铁吸力分析

吸盘式电磁铁在制动器和离合器上的应用很多。在电梯行业，有圆盘式制动器，板块式制动器、碟刹式制动器等多种形式。在本文中，笔者以圆盘式电磁铁为例，对吸盘式电磁铁的吸力情况作一个粗浅的分析，供读者参考。

Sorption Kinetic Analysis for the Removal of Copper(Ⅱ) by Using Biofilm

The biosorption of copper(Ⅱ) ions onto biofilm was studied in a batch system with respect to the temperature, initial pH value and biofilm sorbent mass. The biomass exhibited the highest copper(Ⅱ) sorption capacity under the conditions of room temperature, initial pH value of 6.0 and the sorbent mass 8 g. The experimental data were analyzed using four sorption kinetic models, the pseudo-first order, the Ritchie second order, the modified second order and the Elovich equations to determine the best-fit equation for the sorption of metal ions onto biofilm. Comparing with the sum of squared-errors, the results show that both the Ritchie second order and modified second order equations can fit the experimental data very well.

Adsorption mechanism of expanded graphite for oil and dyes

Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firstly studied. And then stepwise adsorption for oils was carried out with EG which has been saturated firstly by dyes, the difference between adsorbance of oil on EG was checked with deviation analysis. Scanning electronic microscopy （SEM） analysis was used to show structure difference of EG adsorbed different adsorbates. These used adsorbates were SD300 oil, basic fuchsine, Auramine lake yellow O and acid brilliant red 3B. The adsorption isotherm of dyes on EG is type 11 or type 1, and their equilibrium adsorbances are less than 1.0 g/g. While, adsorbance for SD300 oil can reach 104.5 g/g. Deviation analysis for stepwise adsorbances of oil shows no statistical significance. EG saturated firstly by dyes, still has an average adsorption capacity of 35 g/g for SD300 oil, and it does not change with the initial dyes concentration. SEM photos illustrate the adsorption of oil on EG is mainly filling, In the adsorption of dyes, there is severe breakage of the V-type pore and shrinkage of the particle. Kinetic difference is analyzed also.

An improved theoretical procedure for the pore-size analysis of activated carbon by gas adsorption

Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.

Bio-solubilization of Chinese lignite II:protein adsorption onto the lignite surface

Lignite bio-solubilization is a promising technology for converting solid lignite into oil.This study concerns the adsorption of lignite-solubilizing enzymes onto the lignite surface.Adsorption capacity, infrared spectral analysis and driving forces analysis are studied as a way to help understand the bio-solubilization mechanism.The results show that the amount of lignite bio-solubilization is proportional to the amount of adsorbed lignite-solubilizing enzymes.An increase in lignite-solubilizing enzyme adsorption of 10% leads to a 7% increase in lignite bio-solubilization.However, limited amounts of enzymes can be adsorbed by the lignite, thus resulting in low percentages of bio-solubilization.Infrared spectral analysis shows that side chains, such as hy-droxyl and carbonyl, of the lignite structure are the main, and necessary, structures where lignite-solubilizing enzymes attachto the lignite.Furthermore, driving force analysis indicates that the electrostatic force between lignite and enzymes is the main adsorption mechanism.The forces are influenced by solution pH levels, the zeta potential of the lignite and the isoelectric points of the en-zymes.

Thermodynamic analysis of simplified dual-pressure ammonia-water absorption power cycle

A simplified dual-pressure ammonia-water absorption power cycle(DPAPC-a) using low grade energy resources is presented and analyzed.This cycle uses turbine exhaust heat to distill the basic solution for desorption.The structure of the cycle is simple which comprises evaporator,turbine,regenerator(desorber),absorber,pump and throttle valves for both diluted solution and vapor.And it is of high efficiency,because the working medium has large temperature difference in evaporation and small temperature difference in absorptive condensation,which can match the sensible exothermal heat resource and the cooling water simultaneously.Orthogonal calculation was made to investigate the influence of the working concentration,the basic concentration and the circulation multiple on the cycle performance,with 85-110 ℃ heat resource and 20-32 ℃ cooling water.An optimum scheme was given in the condition of 110 ℃ sensitive heat resource and 20 ℃ cooling water,with the working concentration of 0.6,basic concentration of 0.385,and circulation multiple of 5.The thermal efficiency and the power recovery efficiency are 8.06 % and 6.66%,respectively.The power recovery efficiency of the DPAPC-a is 28.8% higher than that of the steam Rankine cycle(SRC) and 12.7% higher than that of ORC(R134a) under the optimized situation.

Determination of the Biosorption of Cd（ II ） by Coconut Fiber

The coconut fiber is produced in large quantities in Brazil, even though very small quantities are being used by some industries, mainly cordage mats and handicrafts. An alternative usage would be the use of these fibers in biosorption of heavy metals from aqueous solutions. This present study aimed to evaluate the potentiality of cadmium biosorption by coconut fiber. The coconut fibers were used at kinetic analysis, influence ofpH and adsorption isotherms were also carried out. It can be concluded that there is great potential for the use of coconut fiber, and the optimum pH for adsorption was around 5.0. The adsorption kinetics is fast and equilibrium occurs within 120 min. The Langmuir isotherm was considered the most suitable to describe the experimental data.

Relationship between breakthrough curve and adsorption isotherm of Ca(Ⅱ)imprinted chitosan microspheres for metal adsorption

In this work, an equilibrium-dispersion model was successfully established to describe the breakthrough performance of Ca（Ⅱ） imprinted chitosan （Ca（Ⅱ）-CS） microspheres packed column for metal adsorption, and the assumptions of Langmuir isotherms and axial dispersion controlled mass transfer process were confirmed. The axial dispersion coefficient in Ca（Ⅱ）-CS microspheres packed column was found to be almost proportional to the linear velocity and fit for prediction through single breakthrough test. Sensitivity analysis for breakthrough curve indicated the axial dispersion coefficient as well as Langmuir coefficient was sensitive variable for deep removal requirement. The retrieval of the adsorption isotherms of Ca（Ⅱ）-CS microspheres from breakthrough curve was fulfilled by modelling calibration. A strategy based on the correlation between adsorption isotherms and breakthrough performance was further proposed to simplify the column adsorption design using absorbents with small/uniform size and fast adsorption kinetics like Ca（Ⅱ）-CS microspheres to cut down the gap between lab and industry.

Effect of Colored Sticky Cards on Non-target Insects

Field experiments to evaluate four different colored sticky cards for trapping non-target insects were conducted in an organic maize field in the Heinigou region of China. Yellow, blue, green, and red sticky cards were used to trap insects in the field. The total number of insects species caught was 54, with 3,862 individuals recorded. Over half of the specimens caught were non-target insects, including phytophagous insects, particularly dipteran species(including many mosquitoes)(50.3%), followed by target pests(37.0%), and beneficial insects(12.7%). Statistical analysis revealed a significant difference in attraction to target pests, non-target pests, and beneficial insects among treatment groups. The results showed that higher numbers of target pests(Myzus persicae Sulzer, Empoasca flavescens Fabricius, Nysius ericaecshinly Schilling) were caught on yellow sticky card traps compared with blue, green, or red sticky card traps, indicating that yellow was the best trap color for target pests, with green and blue being progressively less attractive. For non-target insects, including phytophagous insects, flies, and mosquitoes,higher numbers of were caught on blue sticky card traps compared with yellow,green, or red sticky card traps. Our study indicated that blue was the most attractive color for flies, especially for the housefly, Musca domestica Linnaeus. Our study also showed that most beneficial insects exhibited preferences to particular trap color characteristics: yellow was the most attractive color for parasitic wasps and lady beetles; blue was the most attractive color for hoverflies and honeybees. In contrast,green and red had no significant attraction to beneficial insects.

Rotordynamic forces generated by discharge-to-suction leakage flows in centrifugal pumps

In order to investigate the flow-induced vibration in the shroud passage of centrifugal pump and predict rotordynamic forces of centrifugal pump rotor system, an analysis of rotordynamic forces arising from shrouded centrifugal pump is presented. CFD techniques were utilized to analyze the full three-dimensional viscous, primary/secondary flow field in a centrifugal pump impeller to determine rotordynamic forces. Multiple quasisteady solutions of an eccentric three-dimensional model at different whirl frequency ratios yielded the rotordynamic forces. The skew-symmetric stiffness, damping, and mass matrices were obtained by second-order leastsquares analysis. Simulation of the coupled primary/secondary flow field was conducted, and the complex flow characteristics in the flow field of a shroud passage were achieved including the mean velocity and pressure, as well as the eddy in a large scale of flow field due to viscosity. The rotordynainic force coefficients were calculated, and the resuhs were in good agreement with those of experiment except for the direct inertial coefficient without the consideration of whirling forces from the impeller primary flow passage.

Entropy Analysis of NH_3/H_2O Absorption-Compression Heat Pump

The absorption-compression heat pump （ACHP） has been considered as an effective approach to recover and utilize low-grade heat sources. In the present study, the first and second law thermodynamic analyses of the ACHP with NH3/H20 as working fluid were performed. Thermodynamic properties of each point and heat transfer rate of each component in the cycle under basic operation conditions were calculated from the first law analysis. Following the second law of thermodynamics, the entropy generation of each component and the total entropy generation of the system were obtained. The effect~ of the heating temperature, heat source temperature, and compression ratio on the coefficient of performance （COP） and the total entropy generation （ STot ） of the system were examined. The results show that the increase in COP corresponds to a decrease in STot, and vice versa; besides, for certain operating conditions, an optimum compression ratio in the NH~/H20 ACHP exists.

Analysis of H_2S Tolerance of Pd-Cu Alloy Hydrogen Separation Membranes

The presence of a limited amount of H2S in H2-rich feed adversely affects the Pd-Cu membrane permeation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to predict the S-tolerant performance of the Pd-Cu membranes in presence of H2S under the industrial water-gas-shift(WGS) reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H2S and H2 on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly depended on the pressure ratio of H2S to H2, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cubic and face centered cubic(bcc or fcc)] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H2S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H2S to H2 over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating conditions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.

Thermodynamic Analysis of Double Effect Absorption System along with Boiler and Cooling Tower

Many researchers have studied single and double effect absorption cycles based on first and second lows of thermodynamics But so far the relation of different parameters inside these cycles to the second law of thermodynamics in boiler and cooling tower has not been investigated. In this paper, a system comprised of a series flow double effect water-Lithium bromide absorption chiller, a boiler and a cooling tower is studied based on the first and second laws of thermodynamics, and also exergy analysis is investigated. For this purpose, mass and energy conservation laws governing the system are written, and coefficient of performance of the system, exergy destruction （loss） of each component and exergy efficiency have been calculated.

Modeling of Water Vapor Condensation by Using Computer Methodology

The excessive moisture has an adverse effect on the building materials structure. Most standard construction materials are characterized by porous structure, resulting in the ability to absorb water in liquid and gaseous phases in the inner pores. Under certain conditions, water fills the pores within the structure of building material and then moves back to its surrounding. Many technical studies have shown that monitoring the moisture transport is mainly based on experimental methods. This work is based on models of transport of moisture in building physics, i.e., the description of the moisture behaviour of building materials based on physical laws models （KRISCHER, KIESSL）. The aim of this work is to obtain the parameters of distribution of moisture for calculation capillary conductivity coefficient for practical using by means of non-destructive method. The authors have now developed all the software required to perform a boundary element analysis of problems in potential flow. The examples which the authors can analyse will, however, be restricted to homogenous domains.

Adsorption behavior of molybdenum onto D314 ion exchange resin

The adsorption behavior of molybdenum onto D314 was studied with the static adsorption method. The adsorption process was analyzed from thermodynamic and kinetic aspects. The experimental results show that the equilibrium adsorption data conform satisfactorily to the Langmuir equation. In the adsorption process of D314 for molybdenum, the enthalpy change ΔH is positive when temperature is in the range of 298-338 K, which indicates that the adsorption is an endothermic process, and the elevated temperature benefits to the adsorption. Kinetic analysis shows that the adsorption rate is controlled by intraparticle diffusion and chemical diffusion at the same time. The adsorption mechanism of molybdenum onto D314 was discussed based on IR spectra.

Design and energy absorption enhancement of vehicle hull under high dynamic loads

V-shape hulls are widely used in peacekeeping efforts such as demining vehicles in order to deflect the blast energy and reduce the effects of mine blast. Blast resistant design and energy absorption enhancement of V-shape plates were carried out using finite element analysis package ABAQUS. Various geometries of V-shape plates with and without interlayer of materials like Al-foams and honeycomb were employed to analyze their effects on the deformation of the plate and applied stresses and strains. The results obtained show that application of metallic foams leads to better response of the plate and consequently results in more energy dissipation, less dame to vehicle and enhances crew survivability.

The suction force effect analysis of large civil aircraft ditching

The research on ditching is indispensable for civil airplanes made in China to obtain the airworthiness certificates.The suction force effect in the ditching process is a hot and difficult research topic.In this paper,the explicit method is employed to solve the discrete Lagrangian finite element equations.The Eulerian finite volume method(FVM) is used to solve the Eulerian control equations;the fluid-solid coupling is realized through the general coupling method.The model of large civil airplane ditching is simulated by Dytran and the model test in tank is carried out in the same condition.Based on the analysis on the impacts and generation of the suction force and a numerical example,we obtain the accurate ditching pressure and pitch angle,as well as the results from the simulation and test.The estimated pressure and pitch angles are consistent with the results in the test.In the simulation,where the suction force is considered,the attitude-time history curve is very similar to the one of the tests,whereas the attitudes in the calculation without suction force is far different from the test.It can be concluded from the results that the suction force is the key impact in ditching calculation and can be simulated by general coupling method.In addition,different weight characteristics and different initial pitch angles both result in different pressures of ditching.

Comparison of Phosphorus Sorption by Light-Weight Aggregates Produced in the United States

In this study, phosphorus(P) sorption of thirteen light-weight aggregates(LWAs) from USA was compared during batch equilibrium experiments in order to identify those materials which had the highest P sorption capacity for further study. Seven different levels of sorption activity were observed, which were broadly grouped into three categories—high performing, middle performing, and low performing aggregates. Chemical analysis of Ca, Al, Fe, and Mg was used to describe the differences between LWAs. There was a significant correlation between cation(especially Al, Ca, Fe, and Mg) content and P sorbed. Langmuir isotherms were used to describe P sorption maximum and binding affinity for four of the top five performing LWAs, Universal, Stalite "D", Stalite "Mix", and TXI.The fifth aggregate, Lehigh, exhibited more complex sorption, and was better described by the Freundlich isotherm. Universal had a mean P sorption at the highest concentration of 824 mg kg-1, well above its calculated sorption maximum(702 mg kg-1), and also had the highest binding affinity(1.1 L mg-1). This experiment suggests that the top performing LWA(Universal) may perform poorly in column and field studies due to observed precipitates, which could degrade constructed wetland performance. Other LWAs may exhibit superior field performance due to their high calculated sorption maxima. In general, these results highlight the importance of batch experiments as a first step in identifying materials suitable for column and field experiments.