Design and Structure Optimization of Plenum Chamber with Airfoil Baffle to Improve Its Outlet Velocity Uniformity in Heat Setting Machines

The plenum chamber of a heat setting machine is a key structure for distributing hot air to different air channels.Its outlet velocity uniformity directly determines the heating uniformity of textiles,significantly affecting the heat setting performance.In a traditional heat setting machine,the outlet airflow maldistribution of the plenum chamber still exists.In this study,a novel plenum chamber with an airfoil baffle was established to improve the uniformity of the velocity distribution at the outlet in a heat setting machine.The structural influence of the plenum chamber on the velocity distribution was investigated using a computational fluid dynamics program.It was found that a chamber with a smaller outlet partition thickness had a better outlet velocity uniformity.The structural optimization of the plenum chamber was conducted using the particle swarm optimization algorithm.The outlet partition thickness,the transverse distance and the longitudinal distance of the optimized plenum chamber were 20,686.2 and 274.6 mm,respectively.Experiments were carried out.The experimental and simulated results showed that the optimized plenum chamber with an airfoil baffle could improve the outlet velocity uniformity.The air outlet velocity uniformity index of the optimized plenum chamber with an airfoil baffle was 4.75%higher than that of the plenum chamber without an airfoil baffle and 5.98%higher than that of the conventional chamber with a square baffle in a commercial heat setting machine.

Assessment of the SiC＿p Distribution Uniformity in SiC＿p／Al Composites Made by Powder Metallurgy

In the manufacture of SiC_p/Al completes via powder metallurgy, the method of assessing the distri-bution uniformity of SiC particles is very important. The SiC_p distribution uniformity on each processingprocedure at the macro- and micro-mixed stages was investigated and the methods for determining mix-ture quality were put forward.

The monitoring of burden distribution uniformity and even sintering technology

After expanding the capacity by widening the trolley of the No. 3 sintering machine, severe uneven sintering occurred in the trolley＇ s lateral distribution, which affected the output and quality of sinter. In this study, the quantitative evaluation indices of the burden uniform distribution in the width direction of the sintering machine is introduced for the first time. By measuring the temperature of discharged gas, a plane temperature field is constructed. Through analyzing the temperature field and the burden layer＇ s differential thermal equilibrium, a mathematical model for evaluating the indices, which is an online reflection of the degree of uniform distribution, is built. Following the improvements in burden distribution equipment ,the optimization of the ignition system and the dynamic adjustment of the process ,the problem of uneven sintering in lateral distribution has been solved, and the quality and the yield of sinter have been improved.

Accurate characterization of bubble mixing uniformity in a circular region using computational geometric theory

The present study proposes a novel method based on the geometric theory for measuring the distribution of bubble swarms in the circular region of a direct-contact heat exchanger.It was determined that the mixing is uniform when the average distance between the bubble swarms in the unit circular region is approximately 0.9054,which is the standard reference value.The effect of sample size(i.e.,the number of bubbles)on mixing uniformity was investigated to determine the optimal sample size.It was verified that the metric's accuracy and stability were higher with a sample size of 155.Accordingly,it was proposed to increase the sample size by filling irregular bubbles using a segmentation method,which enabled a further accurate assessment of the mixing uniformity.The mixing uniformity of bubble swarms in the circular region and its maximum internal connection with the square region was accurately quantified.It was revealed that the relative average error increased by approximately 3.47% due to information loss.The proposed method was demonstrated to be rotationally invariant.The present study provided novel insights into evaluating mixing uniformity,which would guide enhanced heat transfer and the effective evaluation of the spatiotemporal characteristics of transient mixing in circular regions or the cross-sections of chemical transport pipelines.

Green's functions for uniformly distributed loads acting on an inclined line in a poroelastic layered site

Based on one type of practical Biot＇s equation and the dynamic-stiffness matrices ofa poroelastic soil layer and half-space, Green＇s functions were derived for unitformly distributed loads acting on an inclined line in a poroelastie layered site. This analysis overcomes significant problems in wave scattering due to local soil conditions and dynamic soil-structure interaction. The Green＇s functions can be reduced to the case of an elastic layered site developed by Wolf in 1985. Parametric studies are then carried out through two example problems.

A CLASS OF RANDOM NUMBER GENERATORS BASED ON WEYL SEQUENCE

The generation of good pseudo-random numbers is the base of many important fields in scientific computing, such as randomized algorithms and numerical solution of stochastic differential equations. In this paper, a class of random number generators （RNGs） based on Weyl sequence is proposed. The uniformity of those RNGs is proved theoretically. Statistical and numerical computations show the efficiency of the methods.

A LEVEL-VALUE ESTIMATION METHOD FOR SOLVING GLOBAL OPTIMIZATION

A level-value estimation method was illustrated for solving the constrained global optimization problem. The equivalence between the root of a modified variance equation and the optimal value of the original optimization problem is shown. An alternate algorithm based on the Newton＇s method is presented and the convergence of its implementable approach is proved. Preliminary numerical results indicate that the method is effective.

A Histogram-Based Static-Error Correction Technique for Flash ADCs

High-speed, high-accuracy data converters are attractive for use in most RF applications. Such converters allow direct conversion to occur between the digital baseband and the antenna. However, high speed and high accuracy make the analog components in a converter more complex, and this complexity causes more power to be dissipated than if a traditional approach were taken. A static calibration technique for flash analog-to-digital converters （ADCs） is discussed in this paper. The calibration is based onhistogram test methods, and equivalent errors in the flash ADC comparators are estimated in the digital domain without any significant changes being made to the ADC comparators. In the trimming process, reference voltages are adjusted to compensate for static errors. Behavioral-level simulations of a moderate-resolution 8-bit flash ADC show that, for typical errors, ADC performance is considerably improved by the proposed technique. As a result of calibration, the differential no.nlinearities （DNLs） are reduced on average from 4 LSB to 0.5 LSB, and the integral nonlinearities （INLs） are reduced on average from 4.2 LSB to 0.35 LSB. Implementation issues for this proposed technique are discussed in our subsequent paper, “A Histogram-Based Static-Error Correction Technique for Flash ADCs： Implementation Aspects. ”

Random step maneuver algorithm with normally distributed starting times

The random step maneuver with uniformly distributed starting times has the disadvantage that it cannot focus the starting time on the more efficiency time. It decreases the penetration probability. To resolve this problem, a random step penetration algorithm with normal distribution starting time is proposed. Using the shaping filters and adjoint system method, the miss distance with different starting times can be acquired. According to the penetration standard, the time window ensuring successful penetration can be calculated and it is used as the 3σ bound of the normally distributed random maneuver. Simulation results indicate that the normally distributed random maneuver has higher penetration probability than the uniformly distributed random maneuver.

Thermal explosion of a reactive gas mixture at constant pressure for non-uniform and uniform temperature systems

In this study,the approximate and exact solutions for the stationary-state of the solids model with neglecting reactant consumption for both non-uniform and uniform temperature systems were applied on gas ignition under a constant pressure condition.The criticality conditions for a slab,an infinite cylinder,and a sphere are determined and discussed using dimensionless temperatures under constant ambient and surface temperatures for a non-uniform temperature system.Exact solution for a Semenov model with convection heat loss was also presented.The solution of the Semenov problem for constant volume or density as a solid and constant pressure were compared.The critical parameterδis calculated and compared with those of Frank-Kamenetskii solution values.The validation of the calculated ignition temperatures with other exact solution and experimental results were offered.The relation between critical parameters form Semenov and F.K.models solution was introduced.

Effect of Different Types of Structural Configuration on Air Distribution in a Compact Purification Device

In some old industrial plants,in order to meet the increasingly strict requirements of pollutant emission limits,it is necessary to install the compact filtration and/or purification devices in a given narrow machine room.Different types of structural configuration might influence air distribution inside these devices.The unreasonable air distribution might lead each part of filtration or purification media to operating at largely different air flow rates.Based on a computational fluid dynamics(CFD)model,this study explores the influence of different outlet positions and different upper heights on the flow field inside chamber.The porous medium model is employed to simulate the air flow in porous media.The changing structural configurations include three positioning cases of the outlet opening and eight height cases of the upper chamber.The root mean square is defined as the non-uniformity coefficient to evaluate the uniformity of air flow distribution.The results show that the farther distance between inlet and outlet openings will bring more uniform air distribution,and the increasing height of upper chamber totally trends to exhibit more uniform air distribution.

Sequential Experiment Design Method Based on Uniformity and Distortion of Responses

With the development of modern electronic countermeasure technology,the fight between radar jamming and anti-jamming in aviation military has become increasingly fierce.There are some special requirements for radar countermeasure experiments.For example,such experiments are often divided into several stages,and responses of the previous stages will become factors of the next stages.Moreover,the experiment design can only consider some typical level values of the factors.However,the experiment factors are mostly continuous variables.Thus when there are some jumps in the response,and the value granularity of the factor level is large,the responses fail to reflect the distortion process,which makes it difficult to explore the radar performance boundary.Therefore,it is necessary to study the sequential experiment design method with the optimization goals of response uniformization and response distortion process characterization.In this paper,a sequential experiment design strategy based on Kriging model is established.Firstly,Kriging model is used to fit the initial experimental data to obtain the response surface.In order to enhance the uniformity of response distribution,Shannon entropy is applied to the objective function as the measure of uniformity.While for the situation of response distortion,we consider replacing the existing experiment points with those whose corresponding responses have a larger gradient norm.It means that the response value near these points will change rapidly,so they are more valuable for research.Then we use the peak surface in the three-dimensional space to intuitively verify the effect of the above algorithms on response uniformization and response distortion process characterization,and use the simulated annealing algorithm to solve them.The simulation results show that our sequential experiment strategy has a good effect.Finally,we apply the strategy to the practical problem of radar countermeasure experiment,and the obtained results also perform well.

Investigation of distribution uniformity of distributor for biogas slurry application based on CFD analysis

A horizontal distributor for biogas slurry application was proposed to explore the distribution performance through CFD analysis and verified by field test.The rheological properties of biogas slurry were analyzed at first,and key parameters were obtained for the next simulation.The effects of distribution modes,inlet direction,and outlets number on the velocity distribution of flow field and mass flow rate of the horizonal distributor were investigated by CFD simulations.Results of rheological properties indicated that biogas slurry was a non-Newtonian fluid and exhibited shear-thinning behavior.It can be well described by power-law model.The simulation results showed that the geometry of rotor,especially the block numbers was the main factor that determining the fluid movement and trajectory of distribution and output.The mode rotor 1 with two blocks reached the lowest variable coefficient of mass flow rate(4.49%),indicating a higher degree of uniformity.The upward inlet direction would obtain less dead zone,and the distributor with an even outlets number would possess more uniform distribution and less dead zone.The field test of the distributor with rotor 1,upward inlet direction,and 24 outlets has been carried on to verify the simulation results,the variable coefficient of mass flow was 13.06%,which was slightly higher than the simulation(9.23%),but it still within the range of requirement(<15%).The proposed model and the findings of this work are of guiding significance for the study of the utilization technology and equipment of liquid biogas residue.

Optimization of movable irrigation system and performance assessment of distribution uniformity under varying conditions

The evaluation of the performance of distribution uniformity by linearly moved irrigation system(LMIS)should consider the impacts of non uniformity of the water on crop yield.With increasing pressures to improve water use efficiency,plant productivity and farm profitability,questions continue to be raised concerning the future direction of irrigated agriculture.This study therefore aimed at evaluating water distribution under LMIS newly designed by the National Research Centre of Fluid Machinery Engineering and Technology,Jiangsu University,China.This article reports the real distribution of irrigation water under the LMIS with respect to sprinkler height above the ground surface as well as the consequence of different operating pressures.Water distribution coefficients used in the performance assessment were Christiansen’s coefficient of uniformity(CU),distribution uniformity(DU),scheduling coefficients(Sc)and the coefficient of variation(CV).The results showed that the mean CU ranged from 82.30%to 93.17%,and mean DU ranged from 70.39%to 88.44%.Also Sc values ranged from 1.13 to 1.42 with CV values ranging from 10.3%to 22.5%.The optimum method and results in this study can provide a reference to the operations for saving water and cost in the application of LMIS.

Study on the flow field uniformity of hydro-floating ship lift combined type hydraulic-driven system based on the residual energy theory

The hydro-floating ship lift originally invented in China is a major innovation in the field of navigation technology.The shaft water levels synchronization of its unique hydraulic-driven system plays a crucial role in reducing the torque of the synchronous shafts and ensuring the safety and stability operation of the ship lift.This study aims to investigate the muti-shaft water level synchronization and the flow velocity uniformity of the combined type hydraulic-driven system.Based on the theory of residual energy,a new index m2 proposed in this study is more suitable for evaluating the flow velocity uniformity of the combined hydraulic-driven system.Finally,the critical value of m2=75 is calculated via the results of the scaled physical mode test as the threshold of water flow uniformity,and it provides a basis for determining the reasonable height of the pressure stabilizing chamber.

Improvement of thickness uniformity and elements distribution homogeneity for multicomponent films prepared by coaxial scanning pulsed laser deposition technique

In conventional pulsed laser deposition （PLD） technique, plume deflection and composition distribution change with the laser incident direction and pulse energy, then causing uneven film thickness and composition distribution for a multicomponent film and eventually leading to low device quality and low rate of final products. We present a novel method based on PLD for depositing large CIGS films with uni- form thickness and stoichiometry. By oscillating a mirror placed coaxially with the incident laser beam, the laser＇s focus is scanned across the rotating target surface. This arrangement maintains a constant re- flectance and optical distance, ensuring that a consistent energy density is delivered to the target surface by each laser pulse. Scanning the laser spot across the target suppresses the formation of micro-columns, and thus the plume deflection effect that reduces film uniformity in conventional PLD technique is eliminated. This coaxial scanning PLD method is used to deposit a CIGS film, 500 nm thick, with thickness uniformity exceeding ±3% within a 5 cm diameter, and exhibiting a highly homogeneous elemental distribution.

Sulfur polymerization strategy based on the intrinsic properties of polymers for advanced binder-free and high-sulfur-content Li–S batteries

Lithium-sulfur(Li-S)batteries are the promising next-generation secondary energy storage systems,because of their advantages of high energy density and environmental friendliness.Among numerous cathode materials,organosulfur polymer materials have received extensive attentions because of their controllable structure and uniform sulfur distribution.However,the sulfur content of most organosulfur polymer cathodes is limited(S content<60%)due to the addition of large amounts of conductive agents and binders,which adversely affects the energy density of Li-S batteries.Herein,a hyperbranched sulfur-rich polymer based on modified polyethyleneimine(Ath-PEI)named carbon nanotubeentangled poly(allyl-terminated hyperbranched ethyleneimine-random-sulfur)(CNT/Ath-PEI@S)was prepared by sulfur polymerization and used as a Li-S battery cathode.The high intrinsic viscosity of Ath-PEI provided considerable adhesion and avoided the addition of PVDF binder,thereby increasing the sulfur content of cathodes to 75%.Moreover,considering the uniform distribution of elemental sulfur by the polymer,the utilization of sulfur was successfully improved,thus improving the rate capability and discharge capacity of the battery.The binder-free,sulfur-rich polymer cathode exhibited ultra-high initial discharge capacity(1520.7 mAh g^(−1) at 0.1 C),and high rate capability(804 mAh g^(−1) at 2.0 C).And cell-level calculations show that the electrode exhibits an initial capacity of 942.3 mAh g^(−1) electrode,which is much higher than those of conventional sulfur-polymer electrodes reported in the literature.

One-dimensional nonlinear consolidation of soft clay with the non-Darcian flow

Based on the non-Darcian flow law described by exponent m and threshold gradient i 1 under a low hydraulic gradient and the classical nonlinear relationships e-lgσ′ and e-lgk v (Mesri and Rokhsar, 1974), the governing equation of 1D nonlinear consolidation was modified by considering both uniform distribution of self-weight stress and linear increment of self-weight stress. The numerical solutions for the governing equation were derived by the finite difference method (FDM). Moreover, the solutions were verified by comparing the numerical results with those by analytical method under a specific case. Finally, consolidation behavior under different parameters was investigated, and the results show that the rate of 1D nonlinear consolidation will slow down when the non-Darcian flow law is considered. The consolidation rate with linear increment of self-weight stress is faster than that with uniform distribution one. Compared to Darcy's flow law, the influence of parameters describing non-linearity of soft soil on consolidation behavior with non-Darcian flow has no significant change.

Cuckoo search with varied scaling factor

Cuckoo search （CS）, inspired by the obligate brood parasitic behavior of some cuckoo species, iteratively uses L6vy flights random walk （LFRW） and biased/selective random walk （BSRW） to search for new solutions. In this study, we seek a simple strategy to set the scaling factor in LFRW, which can vary the scaling factor to achieve better performance. However, choosing the best scaling factor for each problem is intractable. Thus, we propose a varied scal- ing factor （VSF） strategy that samples a value from the range [0,1] uniformly at random for each iteration. In addition, we integrate the VSF strategy into several advanced CS vari- ants. Extensive experiments are conducted on three groups of benchmark functions including 18 common test functions, 25 functions proposed in CEC 2005, and 28 functions intro- duced in CEC 2013. Experimental results demonstrate the ef- fectiveness of the VSF strategy.

Product of Uniform Distribution and Stirling Numbers of the First Kind

Let Vk=u1u2……uk, ui＇s be i.i.d - U（0, 1）, the p.d.f of 1 - Vk＋l be the GF of the unsigned Stirling numbers of the first kind s（n, k）. This paper discusses the applications of uniform distribution to combinatorial analysis and Riemann zeta function; several identities of Stifling series are established, and the Euler＇s result for ∑ Hn/n^k-l, k ≥ 3 is given a new probabilistic proof.