Numerical investigation of granular mixing in an intensive mixer:Effect of process and structural parameters on mixing performance and power consumption

Discrete element method(DEM)simulations of particle mixing process in an intensive mixer were conducted to study the influence of structural and process parameters on the mixing performance and power consumption.The DEM model was verified by comparing the impeller torque obtained from simulation with that from experiment.Impeller and vessel torque,coordination number(CN)and mixing index(Relative standard deviation)were adopted to qualify the particle dynamics and mixing performance with different parameters.A method based on cubic polynomial fitting was proposed to determine the critical mixing time and critical specific input work during the mixing process.It is found that the mixing performance and energy efficiency increases with the decrease of impeller offset.The mixing performance is improved slightly with the increase of blade number and the impeller with 3 blades has the highest energy efficiency due to its low input torque.Results indicate that the energy efficiency and the mixing performance increase with the decrease of filling level when the height of granular bed is higher than that of blade.

Analysis of Medical Waste Incinerator Performance Based on Fuel Consumption and Cycle Times

A detailed assessment of an incinerator based on fuel consumption and cycle time data is presented in this paper. The study was conducted at Temeke district hospital for 22 months consecutively covering 654 days of daily data collection on fuel consumption and cycle times. The composition for the medical waste incinerated varied between 15% and 35% for sharps waste and between 65% and 85% for other waste, with mean values of 25% and 75%, respectively. The results revealed poor performance of the incinerator due to higher fuel consumption (above 30 L/cycle). The incineration cycle times were observed to range between 2 and 4 hours, all of which were too high for the loading rates observed (55 - 214 kg). A strong dependency of diesel oil consumption on cycle time was observed due to lack of temperature control leading to continuous fuel flow into the burners. The incineration capacity was very low compared to other incinerators in terms of tons per year. This paper gives an insight on the factors affecting incinerator performance assessed based on diesel oil consumption and cycle times. It can be generalized that the incinerator performance was poor due to several factors ranging from poor incinerator design, operator skills, waste management practices, waste storage practices, etc. The hospital was advised to install a new incinerator with short incineration cycle time (30 - 40 minutes) and lower fuel consumption (10 L/cycle) at a loading rate of 200 kg/cycle.

The Impacts of Building Regulations on the Thermal Performance and Energy Consumption of Residential Buildings in Riyadh City-Saudi Arabia

Riyadh city is the fastest growing city in Saudi Arabia. The rapid urban growth that happened recently in Riyadh was not based on the traditional urban planning principles, which have been established and applied for the city development process. The imported building regulations have created a new urban structures and street patterns. The contemporary urban form in Riyadh city is based mainly on traffic and economic consideration with the neglect of environmental dimensions. This research aims to examine the impacts of building regulations on the thermal performance of residential buildings in Riyadh city, with the ultimate goal of establishing planning guidelines that consider the environmental conditions of the city. The methodology adopted for achieving the aim of this study consists of two phases. First, the literature related to building regulations development in Riyadh, as of 2018, was reviewed. Second, buildings energy simulation was conducted to examine the thermal performance of the typical current status of residential building blocks in Riyadh city, and then several changes to building regulations were made to investigate their impacts on the thermal performance of buildings. The results showed that the impacts of Riyadh building regulations on the thermal performance of residential buildings differ across the evaluated cases. The ratio of building height to street width, urban block street orientation, and building orientation are the main factors affecting thermal performance of buildings within urban block. The study also concludes that adjusting the ratio of building height to the distance between buildings could have a significant impact in reducing cooling loads. This study will help policy makers, planners and designers to investigate the shortcoming in the current building regulations.

Effect of Refrigerant on the Performance of a C3/MRC Liquefaction Process

The Mixed Refrigerant(MR)component is an important factor influencing the performances of natural gas lique-faction processes.However,there is a lack of systematic research about the utilization of propane pre-cooled(C3/MRC).In this paper,this mixed refrigerant cycle liquefaction process is simulated using the HYSYS software and the main influential parameters involved in the process are varied to analyze their influence on the liquefaction rate and power consumption.The results show that an effective way for lowering the power consumption of the compressor consists of reducing the flow through the compressor through optimization of the percentage of mixed refrigerant.The power consumption of the compressor in the hybrid refrigeration process is affected by both flow and pressure ratios.Its specific power consumption can be reduced by increasing the flow and decreasing the pressure ratio at the same time.The increase in refrigerant pressure at the high-pressure end can significantly mitigate the energy loss of the heat exchanger and compressor.

Influential Factors on Deicing Performance of Electrically Conductive Concrete Pavement

The deicing experiment of carbon fiber reinforced electrically conductive concrete （CFRC） slab was conducted in laboratory at first, then the deicing process of CFRC parement was analyzed by means of finite element method （FEM）. At last, based on the energy conservation law and the computing restdts of finite element method, the influential factors including the setting of electric heating layer, environmental temperature, the thickness of ice, material parameters, and deicing power on deicing performance and energy consumption were discussed.

Comparative Performance Evaluation of Large FPGAs with CNFET-and CMOS-based Switches in Nanoscale

Routing resources are the major bottlenecks in improving the performance and power consumption of the current FPGAs. Recently reported researches have shown that carbon nanotube field effect transistors(CNFETs) have considerable potentials for improving the delay and power consumption of the modern FPGAs. In this paper, hybrid CNFET-CMOS architecture is presented for FPGAs and then this architecture is evaluated to be used in modern FPGAs. In addition, we have designed and parameterized the CNFET-based FPGA switches and calibrated them for being utilized in FPGAs at 45 nm, 22 nm and 16 nm technology nodes.Simulation results show that the CNFET-based FPGA switches improve the current FPGAs in terms of performance, power consumption and immunity to process and temperature variations. Simulation results and analyses also demonstrate that the performance of the FPGAs is improved about 30%, on average and the average and leakage power consumptions are reduced more than 6% and 98% respectively when the CNFET switches are used instead of MOSFET FPGA switches. Moreover, this technique leads to more than 20.31%smaller area. It is worth mentioning that the advantages of CNFET-based FPGAs are more considerable when the size of FPGAs grows and also when the technology node becomes smaller.

Impacts of internal R&D on firms’performance and energy consumption:Evidence from Ethiopian firms

In recent decades,with the rapid development of the knowledge economy and science,countries have embraced technical innovation and have gradually increased investment in research and development(R&D).A vast literature indicates that the relationship between R&D and firm performance is highly complex.The evidence suggests that R&D positively influences firm performance,yet findings on the process by which this happens are mixed.Rigorous analyses are required on how R&D investments affect energy consumption.This study explores the impact of R&D investment on the performance and energy consumption of 476 firms in Ethiopia by employing a combination of fixed-effect,propensity score matching,and endogenous treatment effect estimation methods.The empirical results reveal that investment in R&D positively influences both innovation and long-term financial performance but negatively impacts short-term financial performance and energy consumption.The results also show that the impacts of R&D activities vary significantly across different categories of firms,confirming that heterogeneity may be an issue among the firms considered.The results also indicate that the availability of credit is a more important moderating factor in the relationship between R&D investment and firm performance than the legal system is.These results have important implications for firms with growing R&D operations,especially those in developing countries such as Ethiopia.Ethiopian firms should invest more in R&D activities,such as in fundamental and applied research,to improve performance and enhance competitiveness.

Diesel Engine Emissions and Performance Characteristics under Cape Chestnut Biofuel

Cape Chestnut oil was processed to biodiesel through transesterification. Cape Chestnut kennels are reported to have oil content of 60% - 63% [1]. Properties of biodiesel were determined and compared with those of diesel and engine tests done at a constant speed of 1500 RPM on the biodiesel blends to evaluate their performance and emissions characteristics. Performance evaluation was in terms of Brake Specific Fuel Consumption (BSFC), Brake Horse Power (BHP) and Brake Thermal Efficiency (ETE). The engine was initially run on diesel to establish the reference characteristics before running on biodiesel blends. The biodiesel was blended with diesel volumetrically to 80% (B80), 50% (B50), 20% (B20) and 5% (B5) the percentage being the volume of biodiesel in the blended fuel. Diesel fuel had the lowest BSFC followed by B5 whose BSFC was 7.3% higher than that of diesel. BTE for B100 was lower than that of diesel by 20.3% while that of B5 was 7.6% lower. Concentration of SO2 in B100 was 92.7% lower than that of diesel fuel while that of B20 was 24.7% lower. NO and NO2 concentrations for B100 were around 15% higher than that of diesel. Particulate matter of less than 10 μm diameter (PM10) for diesel was found to be 72% of the total collected from all the test fuels as compared to that of biodiesel blends at 28%. The study concluded that Cape Chestnut biodiesel blends containing up to 20% biodiesel can be used in an unmodified diesel engine since their performance and emission characteristics were very similar to that of diesel but with reduced toxic gas emissions therefore friendly to the environment.

Assessment of Incineration Process Performance in a District Hospital Using Statistical Analysis

The objective of this study was to assess the performance of an old existing medical waste incinerator in a district (Temeke) hospital. The medical waste incinerated was grouped into two categories: sharps waste and other waste. The parameters assessed included amounts of sharps and other waste incinerated, amount of fuel used and the incineration cycle time. One incineration cycle was conducted per day and data was collected for 22 months (N = 653). It was established that the total waste incinerated per day ranged from 70 to 120 kg, completing the process between 2 and 4 hrs and consuming 20 to 40 L of fuel per day. The analysis showed further that sharps waste incinerated were 25% of the total waste while other waste incinerated were about 75% on average. The average diesel oil used was 30 L/day and average cycle time was observed to be 3 hrs, both being excessively high indicating that the performance of the incin-erator was poor. The statistical analysis was used to reveal stronger variations in other waste than sharps waste. The PDF plots, skewness and kurtosis values indicated that there were weak variations in the daily diesel oil consumed and incineration cycle time while stronger variations were observed in the other waste compared to sharps waste data. Normalization of the incinerator performance data allowed comparison between different data types also indicating poor performance of the incinerator. Proper segregation at point of generation and proper storage of medical waste was recommended. It was further recommended for the hospital to install a new and efficient incinerator with short incineration cycle time and less fuel consumption.

冬季不同最小通风量模式对肉种鸡育雏育成期生长性能及环控能耗的影响

为研究冬季不同最小通风量模式对肉种鸡育雏育成期舍内环境、生长性能以及环控能耗的影响,试验测试了间歇式通风和连续式通风两种不同的最小通风量通风控制模式,分别比较了两种模式下鸡舍内主要环境质量参数、环控能耗、体重均匀度和抗体效价。结果显示:第一周,连续通风温度高于间歇通风(P>0.05),相对湿度显著低于间歇通风(P<0.05),二氧化碳浓度显著高于间歇通风模式(P<0.05),第2~10周,连续通风温度极显著高于间歇通风(P<0.01),相对湿度极显著低于间歇通风(P<0.01),二氧化碳浓度极显著高于间歇通风模式(P<0.01),同时连续通风鸡舍内环境参数波动度小于间歇通风;试验期间连续通风环控总能耗(7036.01 kW·h)低于间歇通风(7633.02 kW·h),并且连续通风种鸡体重均匀度优于间歇通风;H5N1亚型禽流感病毒抗体效价显著高于间歇通风(P<0.05),H7N9亚型禽流感病毒抗体效价极显著高于间歇通风(P<0.01)。研究表明,冬季肉种鸡育雏育成期采用连续通风的最小通风量模式对比间歇通风的最小通风量模式,可以获得更加稳定的舍内环境,雏鸡生长性能以及免疫效果更优,且能源消耗更少。

“双循环”下我国数字文化消费及其影响因素研究

在“双循环”新发展格局下,数字化、网络化、智能化普及形成的数字文化消费在文化消费中占据了重要地位,在促进经济增长、推动文化产业升级转型和高质量发展等方面发挥着显著作用。采用2015—2020年中国28个省份的面板数据,运用双向固定效应模型对数字文化消费特征及其影响因素进行比较分析,结果发现:收入水平、供给水平、互联网发展和创新水平对数字文化消费具有显著正向影响;财政支出与数字文化消费具有显著负相关关系;各因素在东中西部地区均存在差异性;消费者主观性价感知正向影响数字文化消费。根据研究结论,对实现数字文化消费可持续发展、加快构建国内国际双循环提出相应的对策建议。

中国全球价值链地位、环境规制与碳排放绩效

努力实现全球价值链地位攀升与低碳经济发展双目标是中国面临的关键问题。基于2000-2014年中国制造业行业数据,考察全球价值链地位攀升对碳排放绩效的影响与作用机制,可发现:全球价值链地位攀升有助于碳排放绩效改善,其赋能效应在不同类型、技术水平以及污染密集度的行业中存在差异性;能源利用效率与能源消费结构是全球价值链地位作用于碳排放绩效的主要路径,同时环境规制强度的提高可以进一步增强其对碳排放绩效改善的正向作用。我国制造业应全方位、多层次融入全球价值链体系,深化链条间行业的上下游合作,推动制造业内部的能源技术溢出效应转换,对不同行业进行差异化政策支持,同时地方政府也应加强适时监督,规制行业的短视行为。

媒介化消费语境性别凝视的主体转换与边界消融

男性凝视理论维持男权主导性地位,将女性排除在统治框架之外,男女权力的争夺在媒介化消费语境中具象化为“性别凝视权力”的争夺。当代社会呈现出凝视的主体由男性向女性流动的轨迹,但究其根本,女性凝视因剥离了男性凝视的“性化”(性别维度对女性的异化)与“依附”(消费中权力的从属关系),更多的是一种审美化的体验。杂糅型社会语境中凝视主体的边界消融,在资本逻辑下利用数字化媒介平等地物化每一个人。在这样的背景下,刻意寻求凝视主体的身份,实际上又会落入二元对立的陷阱。

反复荷载下圆钢管型钢再生混凝土组合柱耗能能力及延性分析

对11个圆钢管型钢再生混凝土组合柱试件进行了低周反复荷载试验,观察了组合柱的破坏形态及特征,获取了组合柱的滞回曲线、等效粘滞阻尼系数、延性系数及侧向位移角等性能指标,分析了再生粗骨料取代率、型钢截面形式、轴压比、型钢配钢率和圆钢管径厚比等参数对组合柱耗能能力及延性的影响规律。结果表明:反复荷载作用下组合柱呈压弯塑性铰破坏模式;组合柱的荷载-位移滞回曲线饱满呈纺梭形,屈服位移后的等效粘滞阻尼系数在0.30~0.48之间,平均位移延性系数大于3.0,极限侧向位移角介于1/30~1/20之间且均大于规范限值1/50,组合柱表现出良好的耗能能力和延性。此外,组合柱的耗能能力和延性受再生粗骨料取代率的影响较大,全再生混凝土较普通混凝土耗能能力下降14.5%;增加钢管壁厚或型钢配钢率有利于提升组合柱的耗能能力和延性,而增大轴压比则对组合柱的延性和变形不利;内置型钢采用箱型截面时,组合柱耗能及延性最优,与工字型钢相比,采用箱型截面型钢的组合柱耗能能力和延性分别提升了23.5%和51.9%。

高管在职消费对上市高新技术企业创新绩效的影响——基于内部控制调节视角的实证研究

选取2018—2022年中国沪深A股上市高新技术企业数据,构建高管在职消费和企业创新绩效之间关系的实证分析模型,并探究内部控制对两者关系的调节作用。实证研究发现:高管在职消费正向促进上市高新技术企业创新绩效,内部控制负向调节二者关系。上市高新技术企业应重视高管在职消费这一隐性激励,同时建设合理适度的内部控制机制,从而更好地促进企业创新绩效提升。

河南农村建筑能效提升改造

为了解目前河南省农村建筑的节能发展现状,对河南省农村现有建筑围护结构的热工性能进行了调研和总结。结果表明,既有农村建筑的墙体、屋面和门窗等的热工性能整体较差,导致供暖和制冷能耗很大。选取典型河南省农村建筑进行了围护结构改造设计,利用PKPM软件对改造前后的建筑能效提升率和经济性进行了计算和对比,分析得出可依据屋面、外墙、外门窗的优先顺序来确定既有农村建筑能效提升路线。其中:对屋面进行改造,其能效提升率相对较高、成本较低,保温层厚度可选取大于50 mm;对外墙进行改造,保温层厚度可选取大于40 mm,当有多面外墙需要改造时,优先改造北面墙。该改造方案可为既有农村建筑的节能改造提供参考,达到节能的目的。

Optimal investment and consumption with forward preferences and uncertain parameters

We introduce and analyze a class of forward performance criteria in incomplete markets in the presence of model ambiguity.Incompleteness stems from general investment constraints,while model uncertainty is represented by a convex and compact set of plausible model parameter processes.Following the max-min criteria in traditional(backward)robust control,we formulate similar criteria for the robust forward performance processes and focus on the rich class of time-monotone processes.We provide a novel PDE characterization and a semi-explicit saddle-point construction of the robust forward performance criteria and their optimal policies.Furthermore,we present additional results within the class of homothetic constant relative risk aversion(CRRA)processes.Within this class,we investigate the relationship between forward performance processes on wealth and those on consumption,establishing an interesting dominance through time.

基于Cruise的重型商用车性能匹配分析

针对重型商用车动力系统开发周期长、成本高的问题,该文首先参考法规基于MATLAB编写程序生成需要的换挡策略,再通过AVL Cruise对整车性能匹配进行建模和仿真分析,得到油耗、动力性都满足要求的最优动力方案,并与该方案对应的实测值进行对比分析。结果表明,仿真结果与实测结果基本吻合,模型仿真可以代替实测对整车性能提前评估,缩短产品开发周期和成本。

基于功耗计数器的处理器功耗实时估算方法

针对现有的2类处理器功耗实时估算方法的不足,本文开发了一种基于功耗计数器的处理器功耗实时估算方法。该方法结合了基于性能事件计数器和基于电路信号方法的优点,利用功耗计数器记录与处理器功耗密切相关的电路信号的变化次数,能够以较小的观测粒度实时估算处理器的功耗,并且具有较低的硬件开销。本文在龙芯GS364处理器上实现并评估了该方法。结果表明,使用16个功耗计数器可以在512个时钟周期的粒度内实现0.83%的估算误差,与此同时,它的硬件开销只占处理器总面积的0.063%。