Visual Study on Flow and Operational Characteristics of Flat Plate Closed Loop Pulsating Heat Pipes

This paper presents an experimental study including visualization on a flat plate closed loop pulsating heat pipes.It consists of a total of 40 channels with square cross section(2 mm×2 mm,165 mm long) machined directly on an aluminum plate(180 mm×120 mm×3 mm) covered by a transparent plate.The working fluid employed is ethanol.As a result,various flow patterns and their transitions are observed and found to be related to the fluid fill ratio,input heat load and the device orientation.Also the operational characteristics and working mechanism are discussed.

Sensitivity and effect of key operational parameters on performance of a dual-cylinder free-piston engine generator

The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure.

OPERATION AND OPTIMIZATION OF BATCH DISTILLATION FOR A BINARY SYSTEM

Batch distillation,basically different from continuous distillation which is a steady stateprocess,appears to be an unsteady state process in its mathematical description.The theoreticalanalysis of its operation comprises a concomitant consideration of the stage-wise separation andthe equations of material balance as well as enthalpy balance.Based upon the batch distillationpractice of NMP-water system,this paper reveals the necessity and advantage of a computerizedtreatment for this purpose.Numerical results not only explain the experimental phenomena andprovide a design scheme,but also lead to the optimization of the operation condition.

Operation Benefit of Fruit Dealers in Shizishan Street Farm market

This paper mainly discussed the operation benefits of fruit dealers in farm market. Taking fruit dealers in Shizishan Street Farm market in Wuhan City as the research object,this paper introduced current operation situation of fruit dealers and made a descriptive statistical analysis on characteristics of operators,operation situation,and cognitive status. Besides,it introduced the concept of net cost-benefit ratio to reflect the operation benefits. From further analysis on the operation benefits of fruit dealers,it found that there is little difference in the costbenefit ratio between dealers in the farm market. The average net cost-benefit ratio was 11. 94%. Specifically,if the total cost is 100 yuan,the dealer can obtain 12 yuan net profit. In order to find out how cost factors affect the operation benefits,it established a regression model for cost factors and net cost-benefit ratio. According to the survey results,when the wholesale cost increases 10000 yuan,the cost-benefit ratio will increase by 1. 454 percentage points,thus increasing the wholesale investment is helpful for increasing the net cost-benefit ratio; when the loss cost increases 10000 yuan,the cost-benefit ratio will increase by 7. 501 percentage points,thus the dealers can increase the operation benefits through controlling the loss cost and reducing the operation cost. Finally,it came up policy recommendations from the perspective of government and operators.

Operational Mode Identification Based on Sliding Time Window Method and Eigensystem Realization Algorithm

The identification result of operational mode is eurychoric while operational mode identification is investigated under ambient excitation,which is influenced by the signal size and the time interval.The operational mode identification method,which is based on the sliding time window method and the eigensystem realization algorithm(ERA),is investigated to improve the identification accuracy and stability.Firstly,the theory of the ERA method is introduced.Secondly,the strategy for decomposition and implementation is put forward,including the sliding time window method and the filtration method of modes.At last,an example is studied,where the model of a cantilever beam is built and the white noise exciting is input.Results show that the operational mode identification method can realize the modes,and has high robustness to the signal to noise ratio and signal size.

Stability evaluation method of large cross-section tunnel considering modification of thickness-span ratio in mechanized operation

Purpose-This study aims to research the large cross-section tunnel stability evaluation method corrected after considering the thickness-span ratio.Design/methodology/approach-First,taking the Liuyuan Tunnel of Huanggang-Huangmei High-Speed Railway as an example and taking deflection of the third principal stress of the surrounding rock at a vault after tunnel excavation as the criterion,the critical buried depth of the large section tunnel was determined.Then,the strength reduction method was employed to calculate the tunnel safety factor under different rock classes and thickness-span ratios,and mathematical statistics was conducted to identify the relationships of the tunnel safety factor with the thickness-span ratio and the basic quality(BQ)index of the rock for different rock classes.Finally,the influences of thickness-span ratio,groundwater,initial stress of rock and structural attitude factors were considered to obtain the corrected BQ,based on which the stability of a large cross-section tunnel with a depth of more than 100 m during mechanized operation was analyzed.This evaluation method was then applied to Liuyuan Tunnel and Cimushan No.2 Tunnel of Chongqing Urban Expressway for verification.Findings-This study shows that under different rock classes,the tunnel safety factor is a strict power function of the thickness-span ratio,while a linear function of the BQ to some extent.It is more suitable to use the corrected BQ as a quantitative index to evaluate tunnel stability according to the actual conditions of the site.Originality/value-The existing industry standards do not consider the influence of buried depth and span in the evaluation of tunnel stability.The stability evaluation method of large section tunnel considering the correction of overburden span ratio proposed in this paper achieves higher accuracy for the stability evaluation of surrounding rock in a full or large-section mechanized excavation of double line high-speed railway tunnels.

Numerical Investigation on Effect of Vapor Split Ratio to Performance and Operability for Dividing Wall Column

Operability problem of dividing wall column (DWC) raised by vapor split was investigated by numerically analyzing four cases defined by different compositions of a three-component mixture. DWCs were firstly designed for each case by optimizing the vapor split to the two sides of the dividing wall, and then their feasibilities and total annual costs in operation were evaluated against different vapor split ratios. The analysis on the operability of the DWC for four cases was made based on two scenarios: (1) vapor split is shifted by the vapor resistance difference between the column sections in the two sides of the dividing wall and (2) the feed composition is changed. It was demonstrated that the positioning of the dividing wall and the decision on the vapor split may affect significantly the operability of a DWC.

Optimal scheduling of a township integrated-energy system using the adjustable heat-electricity ratio model

With the expansion and implementation of rural revitalization strategies,there is a constant need for new energy sources for the construction of new townships.Consequently,integrated energy systems with the interconnection and interaction of multiple energy sources are developing rapidly.Biomass energy,a renewable green energy source with low pollution and wide distribution,has significant application potential in integrated energy systems.Considering the application of biomass energy in townships,this study established an integrated biomass energy system and proposed a model to optimize its operation.Lowest economic cost and highest clean energy utilization rate were considered as the objective functions.In addition,a plan was suggested to adjust the heat-electricity ratio based on the characteristics of the combined heat and power of the biomass.Finally,a simulation analysis conducted for a town in China was discussed,demonstrating that the construction of a township integrated-energy system and the use of biomass can significantly reduce operating costs and improve the energy utilization rate.Moreover,by adjusting the heat-electricity ratio,the economic cost was further reduced by 6.70%,whereas the clean energy utilization rate was increased by 5.14%.

Simulation Modeling and Analysis of Operator-Machine Ratio

Based on a simulation model of a semiconductor manufacturer, operator-machine ratio （OMR） analysis is made using work study and time study. Through sensitivity analysis, it is found that labor utilization decreases with the increase of lot size. Meanwhile, it is able to identify that the OMR for this company should be improved from 1 ： 3 to 1 ： 5. An application result shows that the proposed model can effectively improve the OMR by 33%.

Reliability Analysis on Repairable System with Dual Input Closed-Loop Feedback Link Considering Shutdown Correlation Based on Goal Oriented Methodology

Goal oriented( GO) methodology is a kind of success oriented system reliability analysis method and has been used widely.The repairable system with dual input closed-loop feedback link( DICLFL) considering shutdown correlation didn't make reliability analysis accurately based on existing GO methodology. So, a reliability analysis method used to deal with DICLFL considering shutdown correlation is provided based on GO methodology.Firstly, a new operator, which is used to describe DICLFL considering shutdown correlation,whose number is 1,is created and named as Type 9C operator. And then,the formulas of type 9C operator are derived based on Markov process theory. Finally,the new method presented in this paper is adopted to conduct the reliability analysis of an electro-hydraulic servo speed control system. The analysis result is compared with those of Monte Carlo simulation and fault tree analysis( FTA). The comparison results show that this new reliability analysis method based on GO methodology is feasible and meaningful for reliability analysis of repairable systems with DICLFL considering shutdown correlation.Meantime,it will be useful for more other applications.

Non Degeneration of Fibonacci Series, Pascal’s Elements and Hex Series

Generally Fibonacci series and Lucas series are the same, they converge to golden ratio. After I read Fibonacci series, I thought, is there or are there any series which converges to golden ratio. Because of that I explored the inter relations of Fibonacci series when I was intent on Fibonacci series in my difference parallelogram. In which, I found there is no degeneration on Fibonacci series. In my thought, Pascal triangle seemed like a lower triangular matrix, so I tried to find the inverse for that. In inverse form, there is no change against original form of Pascal elements matrix. One day I played with ring magnets, which forms hexagonal shapes. Number of rings which forms Hexagonal shape gives Hex series. In this paper, I give the general formula for generating various types of Fibonacci series and its non-degeneration, how Pascal elements maintain its identities and which shapes formed by hex numbers by difference and matrices.

Automatic Generation of Water Masks from RapidEye Images

Water is a very important natural resource and it supports all life forms on earth. It is used by humans in various ways including drinking, agriculture and for scientific research. The aim of this research was to develop a routine to automatically extract water masks from RapidEye images, which could be used for further investigation such as water quality monitoring and change detection. A Python-based algorithm was therefore developed for this particular purpose. The developed routine combines three spectral indices namely Simple Ratios (SRs), Normalized Green Index (NGI) and Normalized Difference Water Index (NDWI). The two SRs are calculated between the NIR and green band, and between the NIR and red band. The NGI is calculated by rationing the green band to the sum of all bands in each image. The NDWI is calculated by differencing the green to the NIR and dividing by the sum of the green and NIR bands. The routine generates five intermediate water masks, which are spatially intersected to create a single intermediate water mask. In order to remove very small waterbodies and any remaining gaps in the intermediate water mask, morphological opening and closing were performed to generate the final water mask. This proposed algorithm was used to extract water masks from some RapidEye images. It yielded an Overall Accuracy of 95% and a mean Kappa Statistic of 0.889 using the confusion matrix approach.

高容配比光伏电站储能运行方式及其容量配置研究

随着光伏产业的不断发展,高容配比逐步成为光伏电站设计的主流趋势。针对高容配比子阵内部储能优化充、放电策略的问题,文章提出了一种基于工作模式识别的储能运行方式,以实现能量搬移和平抑波动两种非协同的工作目标。综合考虑光伏储能联合系统的发电收益、储能成本、波动特性、典型日类别等信息,构建了以全生命周期净现值最大和平抑波动效果最优为目标的储能容量优化配置数学模型。以东北某大型光伏电站1.8容配比的1 MW光伏子阵作为案例研究对象,优化得到的最佳储能容量为700 kW·h。不同典型日的仿真结果表明,文章所提出的储能运行方式及配置模型可行有效。

某酒店制冷机房运行策略优化

对华东地区某酒店制冷机房运行策略进行了优化,利用能耗模拟软件对多种运行方案进行了仿真分析。结果表明:原方案仅对冷水泵采用变频控制,制冷机房能效比为4.62;优化方案1采取传统变频方式,对冷水泵、冷却水泵、冷却塔风机采用变频控制,制冷机房能效比达到5.32,与原方案相比提升了15.1%;优化方案2通过对冷水机组、冷水泵、冷却水泵、冷却塔风机进行优化控制,制冷机房能效比为5.48,与原方案相比能效比提升了18.6%,且每年可减少约79 t碳排放量,节能效果显著。

卡托普利抑制试验在原发性醛固酮增多症诊断和分型以及临床转归中的应用

背景 原发性醛固酮增多症(PA)作为继发性高血压中发病率最高、心脑血管危害大但手术后治愈率高的疾病,已被各大高血压指南推荐扩大筛查、早期诊断和治疗。但该类患者的确诊、分型和治疗后临床转归判定方式繁多且存在较多争议。卡托普利抑制试验(CCT)因其便捷、安全可直接用于社区、门诊,期望CCT能对PA患者进行全程管理以改善预后。目的 探究CCT对PA的诊断、分型以及临床转归的判断能力。方法 选取2020-10-01—2022-12-30在四川大学华西医院内分泌代谢科接受内分泌性高血压病因筛查并登记的824例患者为研究对象。经筛选后最终370例患者纳入研究,其中123例原发性高血压(EH)患者纳入EH组,247例PA患者分别纳入单侧醛固酮瘤(APA)组81例、特发性醛固酮增多症(IHA)组55例和未分型PA(u-PA)组111例。比较4组间差异并绘制CCT后各指标及联合诊断PA的受试者工作特征(ROC)曲线,确定最佳截断值。其次绘制CCT后各指标诊断APA和IHA亚型的ROC曲线,计算ROC曲线下面积(AUC)评估CCT对APA和IHA的分型判断能力。最后根据术后临床结局将单侧肾上腺切除患者分为3组:未缓解组11例、临床改善组27例和临床缓解组54例,比较3组间差异并判断CCT对APA患者术后临床转归的判断能力。结果 CCT后血浆醛固酮浓度(PAC)对PA的诊断效能最高(AUC=0.921,95%CI=0.893~0.950),最佳截断值为11.7 ng/dL,灵敏度、特异度分别为84.6%和86.0%;CCT后醛固酮/肾素比值(ARR)对PA也有较好的诊断效能(AUC=0.868,95%CI=0.823~0.923),最佳截断值为2.8(ng/dL)/(mU/L),灵敏度、特异度分别为82.2%和81.0%。CCT后PAC>17.0 ng/dL可协助诊断APA亚型,CCT后PAC<11.7 ng/dL同时ARR<2.8(ng/dL)/(mU/L)的患者可排除APA亚型。在接受手术治疗的患者中,有87.2%患者经CCT后PAC<11.7 ng/dL,89.7%患者CCT后ARR<2.8(ng/dL)/(mU/L)均接近术后临床缓解水平(88.0%)。结论 CCT可全程用于PA患者的诊断、分型和临床转归评价,CCT后PAC及CCT后ARR诊断PA的最佳截断值分别为11.7 ng/dL和2.8(ng/dL)/(mU/L),也可用于APA的分型判断以及术后生化缓解的判断。CCT前采血检验临床意义小,可适当简化流程。

IGSA-PID算法的双带式全电调节CVT速比优化控制

双带式全电调节无级变速器(Double-Belt Electro-Mechanical Continuously Variable Transmission,简称DEMCVT)具有两组带传动装置,能够有效提升CVT的承载能力;DEM-CVT具有单带与双带两种工作模式,通过设计基于效率最优的模式切换策略,能够有效提高燃油经济性;采用直流电机调节主从动轮工作半径从而实现速比变化调节,针对DEM-CVT速比控制,设计了针对不同工况的速比控制策略,以PID算法为基础,提出了一种改进算法IGSA对PID算法进行参数优化,并通过建模仿真得到仿真结果,验证了提出的速比控制策略和控制方法的有效性。

超高压拱形爆破片中操作比对爆破压力作用机理仿真研究

十字开槽正拱形爆破片具有响应快、无碎片飞溅等优点,在使用过程中操作比(工作压力与爆破压力的比值)对爆破性能的影响值得研究。对十字开槽正拱形爆破片进行动态爆破试验,并建立有限元仿真模型,通过动态爆破试验结果验证有限元模型的可靠性;对不同操作比下的爆破片爆破性能进行研究,总结爆破压力变化规律,发现随着操作比的增大,爆破压力出现了减小,在部分情况下,与无操作比影响时的相对偏差大于10%,爆破压力的相对偏差随操作比的增加先增大后减小,转折点出现在操作比为30%~70%的范围内,且转折点对应的操作比随拱高的增加逐渐增大,爆破片的拱高增大,爆破压力的相对偏差整体变小,主要原因与残余应力和塑性形变有关。

基于归一化原理的流量计群在线核查方法

目前供热系统中的流量计带病工作较多、流量测量数据可信度低、判断流量计工作情况难。本文研究了利用归一化方法解决流量计群的测量数据不闭合问题,给出了流量及热量的修正方法;分析了总流量变化时各热力站的流量比变化率,以及正常运行的流量计的流量比变化率的区间,证明了利用流量比变化率可实现流量计的云在线核查,为保障智慧供热系统中的数据正确及完整提供了简单、实用的方法。

静置工况条件下掺氢天然气浓度分布规律

利用天然气管道进行掺氢输送已成为氢能及天然气输送领域的热点和重点,但当前业界对于掺氢天然气在管道输送和停输静置过程中是否会自发分层一直存在较大争议。为了厘清该问题,以掺氢天然气在管道中静置这一极端工况为例,基于热力学能量最小原理,推导了在重力场作用下掺氢天然气浓度分布数学模型,并采用Peng-Robinson真实气体状态方程对该数学模型进行了求解,最后研究了甲烷—氢气二元组分混合气体在4种典型场景高度和5种掺氢比下氢浓度随高度的分布规律。研究结果表明:(1)在重力影响下管道顶部和底部的氢浓度存在差异,但其受高度差的影响显著,对于米级的水平管道、几十米级的一般城镇楼宇天然气立管、百米级的高层楼宇天然气立管,氢浓度随高度变化的差异微小,可完全忽略氢分层;(2)对于千米级大落差的掺氢天然气管道,当掺氢比不超过20%时,氢分层仍可忽略,但当掺氢比很高时(例如50%)管道顶部和底部的氢浓度差将超过1%,此时需考虑工程实际情况评估能否忽略氢分层;(3)西气东输某管道考虑真实气体组成、掺氢比20%、管道落差200 m时,各气体组分的浓度随落差高度的分布规律揭示了在实际工程中此类落差高度的掺氢天然气氢分层可忽略。结论认为,对于掺混均匀的掺氢天然气在静置这种最容易发生分层的极端工况下,如果不存在千米级极端大落差和极端大掺氢比,掺氢天然气管道分层现象可完全忽略;该认识从理论上厘清了目前关于掺氢天然气分层现象的争议,对掺氢天然气管道安全输送具有重要指导意义。