Optimal Design of High-Speed Partial Flow Pumps using Orthogonal Tests and Numerical Simulations

To investigate the influence of structural parameters on the performances and internal flow characteristics of partial flow pumps at a low specific speed of 10000 rpm,special attention was paid to the first and second stage impeller guide vanes.Moreover,the impeller blade outlet width,impeller inlet diameter,blade inclination angle,and number of blades were considered for orthogonal tests.Accordingly,nine groups of design solutions were formed,and then used as a basis for the execution of numerical simulations(CFD)aimed at obtaining the efficiency values and heads for each design solution group.The influence of impeller geometric parameters on the efficiency and head was explored,and the“weight”of each factor was obtained via a range analysis.Optimal structural parameters were finally chosen on the basis of the numerical simulation results,and the performances of the optimized model were verified accordingly(yet by means of CFD).Evidence is provided that the increase in the efficiency and head of the optimized model was 12.11%and 23.5 m,respectively,compared with those of the original model.

Design and Characterization of an Aerosol Test Chamber for Emergency Response Patient Contamination Control Simulation and Research

Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an aerosol test chamber are required to examine factors of contamination, decontamination, and cross-contamination. This study presents the design, construction, and a method for characterizing an aerosol test chamber for a full-sized manikin on a standard North Atlantic Treaty Organization litter. The methodology combined air velocity measurements, aerosol particle counts and size distributions, and computational fluid dynamics modeling to describe the chamber’s performance in three dimensions. This detailed characterization facilitates future experimental design by predicting chamber performance for a variety of patient-focused research.

Seismic effectiveness evaluation and optimized design of tie up method for securing museum collections

To quantify the seismic effectiveness of the most commonly used fishing line tie up method for securing museum collections and optimize fixed strategies for exhibitions,shaking table tests of the seismic systems used for typical museum collection replicas have been carried out.The influence of body shape and fixed measure parameters on the seismic responses of replicas and the interaction behavior between replicas and fixed measures have been explored.Based on the results,seismic effectiveness evaluation indexes of the tie up method are proposed.Reasonable suggestions for fixed strategies are given,which provide a basis for the exhibition of delicate museum collections considering the principle of minimizing seismic responses and intervention.The analysis results show that a larger ratio of height of mass center to bottom diameter led to more intense rocking responses.Increasing the initial pretension of fishing lines was conducive to reducing the seismic responses and stress variation of the lines.Through comprehensive consideration of the interaction forces and effective securement,it is recommended to apply 20%of breaking stress as the initial pretension.For specific museum collections that cannot be effectively protected by the independent tie up method,an optimized strategy of a combination of fishing lines and fasteners is recommended.

一种数字后端设计DFT的方法分析

阐述可测试性设计(DFT)的特点。分析一种ASIC设计中DFT的方法,包括定义扫描链、定义测试信号、提取扫描链、写入测试协议,使设计人员可以优化最终芯片制造的功耗、面积和时序。

基于组合DFT方法的ECSP配比设计策略研究

为提高电控固体推进剂(ECSP)配比设计中能量特性参数计算效率以及解决传统配比设计策略未考虑组分含量同步变化的问题,提出了一种基于revDSD-PBEP86-D3(BJ)泛函的组合密度泛函理论(DFT)方法(co-revDSD),将几何优化、振动分析、单点能计算、单点能外推等步骤组合,并结合非迭代三激发电子相关耦合簇(CCSD(T))方法进行了校正,对比了部分有机物生成焓的实验值和co-revDSD方法的计算值;建立了基于评价指数的配比设计策略,基于co-revDSD方法计算了ECSP组分生成焓,绘制了考虑ECSP不同组分含量同步变化时的能量特性参数云图。结果表明,co-revDSD方法可以高效地计算生成焓,部分有机物的实验值和co-revDSD方法的计算值误差在-5%~5%之间;硝酸羟胺(HAN)的生成焓-250.031 kJ·mol^(-1),聚乙烯醇(PVA)的生成焓与重复单元数成正比,比例系数为-219.117;氧化剂/燃料(O/F)比和Al含量的增大在一定范围内均会造成ECSP的能量特性参数的增大,增大Al含量和O/F比可在比冲合适的条件下尽可能降低燃烧温度及燃气平均相对分子质量。

基于Design-Expert优化一款中药空气抑菌剂配方的研究

目的:以多种中药挥发油作为原料,开发一款高效广谱抑菌的空气抑菌剂。方法:选取丁香、艾叶、香茅3种挥发油,采用Design-Expert 12.0中自带的Optimal(custom)试验设计进行最优混料配方筛选试验。通过采样我校饭堂空间空气浮游菌,先按软件设计配方加样抑菌孵育并计数,再拟合出孵育菌落数与各挥发油配方比例的模型方程,最后计算出最佳抑菌效能配方比例,并采用实验室试验和现场试验验证优选配方。结果:利用286组抑菌孵育数据计算得出,孵育菌落数(Y)与各挥发油配方比例之间的拟合方程为Y=17.60A+53.01B+36.76C-106.11AB-84.87AC-63.93BC+782.79A^(2)BC-1178.89AB^(2)C+413.15ABC2。丁香与艾叶、香茅挥发油抑菌的交互作用对孵育菌落数量有显著影响(p<0.05)。最终选择的丁香、艾叶、香茅挥发油比例为45.2:41.6:13.2,该配方的实验室试验和现场试验验证了其抑菌效能良好。结论:中药抑菌挥发油复配后具有明显的增效作用。该配方的空气抑菌剂抑菌效果明显,气味芳香易于被人们接受,具有良好的市场前景和推广价值。

Optimization and Testing for PCR System of Rice by Orthogonal Design

[Objective] This study was to screen the economic or stable PCR system of rice and detect the generality of the selected system in different molecular markers based on PCR.[Method] With DNA extracted from rice leaves by CTAB method as the template,PCR system was optimized by L16(45)orthogonal design.[Result] Clear bands were amplified from 16 different combinations,but the amplification effects and yields had difference.The most economic and applicable system was as follows:20 ng DNA template,150 μmol/L dNT...

Listening Test Design and Teaching

Listening importance attracts researchers' attention.Based on testing responses,typical listening items are introduced and suggestions are proposed to improve listing teaching.

基于机器学习的高效率集成电路DFT技术研究

本文提出了一种基于机器学习的高效率集成电路可测性设计技术.该技术以自动收集的数据作为训练集,以决定系数为评价指标,为每类目标参数选择出最佳预测模型,并预测出基于不同配置参数的可测性设计结构所对应的目标参数,最后使用最优配置推断技术,以目标参数差值的加权和作为衡量指标,输出最优的可测性设计配置参数.实验数据表明,针对可测性设计技术中最重要的测试覆盖率参数,平均预测误差仅为0.0756%;根据目标参数差值的加权和的最小值情况,实现高效推断芯片可测性设计的最优配置参数.该技术的预测效果具有高可靠性,能够在保证高测试覆盖率的前提下,有效减少测试成本和面积开销等.

Optimal Design of Multiple Stress Constant Accelerated Life Test Plan on Non-rectangle Test Region

For optimal design of constant stress accelerated life test（CSALT） with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-I censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method, The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions.

Optimal Design of Multiple Stresses Accelerated Life Test Plan Based on Transforming the Multiple Stresses to Single Stress

For planning optimum multiple stresses accelerated life test plans, a commonly followed guiding principle is that all parameters of the life-stress relationship should be estimated, and the number of the stress level combinations must be no less than the number of parameters of the life-stress relationship. However, the general objective of an accelerated life test（ALT） is to assess thep-th quantile of the product life distribution under normal stress. For this objective,estimating all model parameters is not necessary, and this will increase the cost of test. Based on the theoretical conclusion that the stress level combinations of the optimum multiple stresses ALT plan locate on a straight line through the origin of coordinate, it is proposed that a design idea of planning the optimum multiple stresses ALT plan through transforming the problem of designing an optimum multiple stresses ALT plan to designing an optimum single stress ALT plan. Moreover, a method of planning the optimum multiple stresses ALT plan which can avoid estimating all model parameters is established. An example shows that, the proposed plan which only has two stress level combinations could achieve an accuracy no less than the traditional plan, and save the test time and cost on one stress level combination at least; when the actual product life is less than the design value, even the deviation of the model initial parameters value is up to 20%, the variance of the estimation of thep-th quantile of the proposed plan is still smaller than the traditional plans approximately 25%. A design method is provided for planning the optimum multiple stresses ALT which uses the statistical optimum degenerate test plan as the optimum multiple stresses accelerated life test plan.

Design of Accelerated Life Test Plans——Overview and Prospect

Accelerated life test(ALT) is currently the main method of assessing product reliability rapidly, and the design of efficient test plans is a critical step to ensure that ALTs can assess the product reliability accurately, quickly, and economically. With the promotion of the national strategy of civil-military integration, ALT will be widely used in the research and development(R&D) of various types of products, and the ALT plan design theory will face further challenges. To aid engineers in selecting appropriate theories and to stimulate researchers to develop the theories required in engineering, with focus on the demands for theory research that arise from the implementation of ALT, this paper reviews and summarizes the development of ALT plan design theory. The development of the theory and method for planning optimal ALT for location-scale distribution, which is the most applied and mature theory of designing the optimal ALT plan, are described in detail. Taking this as the center of radiation, some problems that ALT now faces, such as the verification of the statistical model, limitation of sample size, solutions of resource limits, optimization of the test arrangement, and management of product complexity, are discussed, and the general ideas and methods of solving these problems are analyzed. Suggestions for selecting appropriate ALT plan design theories are proposed, and the urgent solved theory problems and opinions of their solutions are proposed. Based on the principle of convenience for engineers to select appropriate methods according to the problems found in practice, this paper reviews the development of optimal ALT plan design theory by taking the engineering problems arising from the ALT implementation as the main thread, provides guidelines on selecting appropriate theories for engineers, and proposes opinions about the urgent solved theory problems for researchers.

Low overhead design-for-testability for scan-based delay fault testing

An efficient design-for-testability （DFT） technique is proposed to achieve low overhead for scan-based delay fault testing. Existing techniques for delay test such as skewed-load or broadside make the test generation process complex and produce lower coverage for scan-based designs as compared with non-scan designs, whereas techniques such as enhanced-scan test can make the test easy but need an extra holding latch to add substantial hardware overhead. A new tri-state holding logic is presented to replace the common holding latch in enhanced-scan test to get a substantial low hardware overhead. This scheme can achieve low delay overhead by avoiding the holding latch on the critical timing scan path. What＇s more, this method can also keep the state and signal activity in the combinational circuit from the scan during data scan-in operation to reduce the power dissipation. Experiment results on a set of ISCAS89 benchmarks show the efficiency of the proposed scheme.

Bayesian optimal design of step stress accelerated degradation testing

This study presents a Bayesian methodology for de- signing step stress accelerated degradation testing （SSADT） and its application to batteries. First, the simulation-based Bayesian de- sign framework for SSADT is presented. Then, by considering his- torical data, specific optimal objectives oriented Kullback-Leibler （KL） divergence is established. A numerical example is discussed to illustrate the design approach. It is assumed that the degrada- tion model （or process） follows a drift Brownian motion; the accele- ration model follows Arrhenius equation; and the corresponding parameters follow normal and Gamma prior distributions. Using the Markov Chain Monte Carlo （MCMC） method and WinBUGS software, the comparison shows that KL divergence is better than quadratic loss for optimal criteria. Further, the effect of simulation outiiers on the optimization plan is analyzed and the preferred sur- face fitting algorithm is chosen. At the end of the paper, a NASA lithium-ion battery dataset is used as historical information and the KL divergence oriented Bayesian design is compared with maxi- mum likelihood theory oriented locally optimal design. The results show that the proposed method can provide a much better testing plan for this engineering application.

Mathematical model for abrasive suspension jet cutting based on orthogonal test design

This paper describes the application of orthogonal test design coupled with non-linear regression analysis to optimize abrasive suspension jet （AS J） cutting process and construct its cutting model. Orthogonal test design is applied to cutting stainless steel. Through range analysis on experiment results, the optimal process conditions for the cutting depth and the kerr ratio of the bottom width to the top width can be determined. In addition, the analysis of ranges and variances are all employed to identify various factors： traverse rate, working pressure, nozzle diameter, standoff distance which denote the importance order of the cutting parameters affecting cutting depth and the kerf ratio of the bottom width to the top width. ~rthermore, non-linear regression analysis is used to establish the mathematical models of the cutting parameters based on the cutting depth and the kerr ratio. Finally, the verification experiments of cutting parameters＇ effect on cutting performance, which show that optimized cutting parameters and cutting model can significantly improve the prediction of the cutting ability and quality of ASJ.

Ethernet Controller SoC Design and Its Low-Power DFT Considerations

In this paper, an Ethernet controller SoC solution and its low power design for testability （DFT） for information appliances are presented. On a single chip, an enhanced one-cycle 8-bit micro controller unit （MCU）, media access control （MAC） circuit and embedded memories such as static random access memory （SRAM）, read only memory （ROM） and flash are all integrated together. In order to achieve high fault coverage, at the same time with low test power, different DFT techniques are adopted for different circuits： the scan circuit that reduces switching activity is implemented for digital logic circuits; BIST-based method is employed for the on-chip SRAM and ROM. According to the fault-modeling of embedded flash, we resort to a March-like method for flash built in self test （BIST）. By all means above, the result shows that the fault coverage may reach 97%, and the SoC chip is implemented successfully by using 0.25 μm two-poly four-metal mixed signal complementary metal oxide semiconductor （CMOS） technology, the die area is 4.8×4.6 mm^2. Test results show that the maximum throughput of Ethemet packets may reach 7Mb·s^1.

Reverse Design and Test of Non-circular Gear & Crank-Rocker & Gear Trains Weft Insertion Mechanism

For the purpose of obtaining satisfactory performance of the non-circular gear & crank-rocker & gear trains (NCCRG) weft insertion mechanism which was proposed in this paper, the ideal kinematic curve of this weft insertion mechanism was given, and the reverse solution models of this mechanism were established. A reverse design and simulation software was compiled based on Visual Basic 6.0 to obtain the mechanism parameters, including the pitch curves and tooth profiles of the non-circular gears. A test-bed of this mechanism was developed according to these parameters. The kinematic performance of this weft insertion mechanism was tested by high-speed video tape recorder with its corresponding video analytical software Blaster's MAS. And the test results were identical with the theoretical calculation. Compared with the conjugate cam weft insertion mechanism which is applied on TT96 rapier loom, under the condition of same weft insertion rate, the variation of acceleration of this mechanism is smaller. This novel weft insertion mechanism can meet the requirements of weft insertion on rapier looms with smooth and steady motion.

Development of a rapid test kit for SARS-CoV-2:an example of product design

We present an example of applying'need-driven'product design principle to the development of a rapid test kit to detect SARS-COV-2(COVID-19).The tests are intended for use in the field and,longer term,for home use.They detect whether a subject is currently infected with the virus and is infectious.The urgent need for large numbers of tests in field setting imposes constraints such as short test time and lack of access to specialist equipment,laboratories and skilled technicians to perform the test and interpret results.To meet these needs,an antigen test based on RT-LAMP with colorimetric readout was chosen.Direct use of swab sample with no RNA extraction was explored.After extensive experimental study(reported elsewhere),a rapid test kit has been fabricated to satisfy all design criteria.

To What Extent does the Nature of the Language Skill being Taught Influence Test Design

There are many various kinds of English language tests in the world,ranging from IELTS(International English Lan⁃guage Testing System)to TOEFL(Test of English as a Foreign Language).All these tests are designed for different purposes relat⁃ing to various groups of testees.Usually the English language test covers the testing of the four language skills of reading,writing,listening and speaking.The essay will discuss the relationship between the nature of four skills and the test design respectively.

Optimal design and dynamic impact tests of removable bollards

Anti-ram bollard systems, which are installed around buildings and infrastructure, can prevent unauthorized vehicles from entering, maintain distance from vehicle-borne improvised explosive devices （VBIED） and reduce the corresponding damage. Compared with a fixed bollard system, a removable bollard system provides more flexibility as it can be removed when needed. This paper first proposes a new type of K4-rated removable anti-ram bollard system. To simulate the collision of a vehicle hitting the bollard system, a finite element model was then built and verified through comparison of numerical simulation results and existing experimental results. Based on the orthogonal design method, the factors influencing the safety and economy of this proposed system were examined and sorted according to their importance. An optimal design scheme was then produced. Finally, to validate the effectiveness of the proposed design scheme, four dynamic impact tests, including two front impact tests and two side impact tests, have been conducted according to BSI Specifications. The residual rotation angles of the specimen are smaller than 30~ and satisfy the requirements of the BSI Specification.