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Geometric optimization model for the solar cavity receiver with helical pipe at different solar radiation

Chongzhe ZOU, Huayi FENG, Yanping ZHANG, Quentin FALCOZ, Cheng ZHANG, Wei GAO

《能源前沿（英文）》 2019年第13卷第2期页码 284-295 doi: 10.1007/s11708-019-0613-3

摘要： In consideration of geometric parameters, several researches have already optimized the thermal efficiency of the cylindrical cavity receiver. However, most of the optimal results have been achieved at a fixed solar radiation. At different direct normal irradiance (DNI), any single optimal result may not be suitable enough for different regions over the world. This study constructed a 3-D numerical model of cylindrical cavity receiver with DNI variation. In the model of a cylindrical cavity receiver containing a helical pipe, the heat losses of the cavity and heat transfer of working medium were also taken into account. The simulation results show that for a particular DNI in the range of 400 W/m to 800 W/m , there exists a best design for achieving a highest thermal efficiency of the cavity receiver. Besides, for a receiver in constant geometric parameters, the total heat losses increases dramatically with the DNI increasing in that range, as well as the temperature of the working medium. The thermal efficiency presented a different variation tendency with the heat losses, which is 2.45% as a minimum decline. In summary, this paper proposed an optimization method in the form of a bunch of fitting curves which could be applied to receiver design in different DNI regions, with comparatively appropriate thermal performances.

关键词： cylindrical cavity receiver 3-D numerical simulation geometric optimization direct normal irradiation

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Viability of a concentrated solar power system in a low sun belt prefecture

Rahul BHATTACHARJEE, Subhadeep BHATTACHARJEE

《能源前沿（英文）》 2020年第14卷第4期页码 850-866 doi: 10.1007/s11708-020-0664-5

摘要： Concentrating solar power (CSP) is considered as a comparatively economical, more efficient, and large capacity type of renewable energy technology. However, CSP generation is found restricted only to high solar radiation belt and installed where high direct normal irradiance is available. This paper examines the viability of the adoption of the CSP system in a low sun belt region with a lower direct normal irradiance (DNI). Various critical analyses and plant economics have been evaluated with a lesser DNI state. The obtained results out of the designed system, subjected to low DNI are not found below par, but comparable to some extent with the performance results of such CSP plants at a higher DNI. The analysis indicates that incorporation of the thermal energy storage reduces the levelized cost of energy (LCOE) and augments the plant capacity factor. The capacity factor, the plant efficiency, and the LCOE are found to be 32.50%, 17.56%, and 0.1952 $/kWh, respectively.

关键词： concentrated solar power direct normal irradiance plant performance plant economics thermal energy storage

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A study on the catalytic performance of Pd/γ-Al

Ruizhi CHU, Xianyong WEI, Zhimin ZONG, Wenjia ZHAO

《化学科学与工程前沿（英文）》 2010年第4卷第4期页码 452-456 doi: 10.1007/s11705-010-0522-9

摘要： A series of Pd/γ-Al O hybrid catalysts were prepared by impregnation and subsequent calcination under microwave irradiation. The catalysts were used for direct synthesis of dimethylether (DME) from syngas. The results show that calcination under microwave irradiation improved both the activity and selectivity of the catalysts for DME synthesis. The optimum power of the microwave was determined to be 420 W. Under such optimum conditions, CO conversion, DME selectivity and time space yield of DME were 60.1%, 67.0%, and 21.5 mmol·mL ·h , respectively. Based on various characterizations such as nitrogen physisorption, X-ray diffraction, CO-temperature-programmed desorption, and Fourier transform infrared spectral analysis, the promotional effect of the microwave irradiation on the catalytic property was mainly attributed to both the higher dispersion of Pd and the significant increase in the adsorption on the CO-bridge of Pd. Microwave irradiation with very high power led to the increase in CO-bridge adsorption and thereby decreased the catalytic activity, whereas the coverage by metallic Pd of the active sites on acidic γ-Al O significantly occurred under microwave irradiation with very low power, resulting in a decrease in the selectivity to DME.

关键词： Pd/γ-Al₂O₃ direct synthesis dimethyl ether calcination under microwave irradiation

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Genomic variations in the counterpart normal controls of lung squamous cell carcinomas

null

《医学前沿（英文）》 2018年第12卷第3期页码 280-288 doi: 10.1007/s11684-017-0580-1

摘要：

Lung squamous cell carcinoma (LUSC) causes approximately 400 000 deaths each year worldwide. The occurrence of LUSC is attributed to exposure to cigarette smoke, which induces the development of numerous genomic abnormalities. However, few studies have investigated the genomic variations that occur only in normal tissues that have been similarly exposed to tobacco smoke as tumor tissues. In this study, we sequenced the whole genomes of three normal lung tissue samples and their paired adjacent squamous cell carcinomas. We then called genomic variations specific to the normal lung tissues through filtering the genomic sequence of the normal lung tissues against that of the paired tumors, the reference human genome, the dbSNP138 common germline variants, and the variations derived from sequencing artifacts. To expand these observations, the whole exome sequences of 478 counterpart normal controls (CNCs) and paired LUSCs of The Cancer Genome Atlas (TCGA) dataset were analyzed. Sixteen genomic variations were called in the three normal lung tissues. These variations were confirmed by Sanger capillary sequencing. A mean of 0.5661 exonic variations/Mb and 7.7887 altered genes per sample were identified in the CNC genome sequences of TCGA. In these CNCs, C:G→T:A transitions, which are the genomic signatures of tobacco carcinogen N-methyl-N-nitro-N-nitrosoguanidine, were the predominant nucleotide changes. Twenty five genes in CNCs had a variation rate that exceeded 2%, including ARSD (18.62%), MUC4 (8.79%), and RBMX (7.11%). CNC variations in CTAGE5 and USP17L7 were associated with the poor prognosis of patients with LUSC. Our results uncovered previously unreported genomic variations in CNCs, rather than LUSCs, that may be involved in the development of LUSC.

关键词： lung cancer counterpart normal control genomic variations

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Decomposition of aqueous chlorinated contaminants by UV irradiation with H

Eunsung KAN,Chang-Il KOH,Kyunghyuk LEE,Joonwun KANG

《环境科学与工程前沿（英文）》 2015年第9卷第3期页码 429-435 doi: 10.1007/s11783-014-0677-6

摘要： In the present study, the decomposition rates of carbon tetrachloride (CCl ) and 2,4-dichlorophenol (2,4-DCP) in water by the ultraviolet (UV) light irradiation alone and H O /UV were experimentally investigated. The detailed experimental studies have been conducted for examining treatment capacities of the two different ultraviolet light sources (low and medium pressure Hg arc) in H O /UV processes. The low or medium UV lamp alone resulted in a 60%–90% decomposition of 2,4-DCP while a slight addition of H O resulted in a drastic enhancement of the 2,4-DCP decomposition rate. The decomposition rate of 2,4-DCP with the medium pressure UV lamp alone was about 3–6 times greater than the low pressure UV lamp alone. In the direct photolysis of aqueous CCl , the medium pressure UV lamp had advantage over the low pressure UV lamp because the molar extinction coefficient of CCl at shorter wavelength (210–220 nm) is about 20 to 50 times higher than that at 254 nm. However, adding H O to the medium pressure UV lamp system rendered a negative oxidation rate because H O acted as a UV absorber being competitive with CCl due to negligible reaction between CCl and OH radicals. The results from the present study indicated significant influence of the photochemical properties of the target contaminants on the photochemical treatment characteristics for designing cost-effective UV-based degradation of toxic contaminants.

关键词： H₂O₂/ultraviolet (UV) light advanced oxidation UV light irradiation chlorinated contaminants photochemical treatment characteristics

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Feedback linearization based control for weak grid connected PV system under normal and abnormal conditions

Rahul SHARMA,Sathans SUHAG

《能源前沿（英文）》 2020年第14卷第2期页码 400-409 doi: 10.1007/s11708-017-0459-5

摘要： This paper proposes a control strategy for interface of distributed energy sources into the weak grid system with a focus on the energy and ancillary services. A novel controller has been designed and implemented to tackle the challenges of coupling terms in the LCL filter, the transient behavior under sudden changes, and the voltage support under fault condition using the feedback linearization technique. The controller proposed has been implemented on the PV system connected with the weak grid using the LCL filter and the performance of the controller has been verified using Matlab/Simulink through simulation under different conditions. The results of the controller proposed have been compared with the conventional PI dual loop controller. The simulation results obtained demonstrate the effectiveness and simplicity of the controller design strategy.

关键词： PV system grid interface feedback linearization inverter LCL filter

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Dynamic in-plane transversal normal stresses in the concrete face of CFRD

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 135-148 doi: 10.1007/s11709-018-0481-7

摘要： Severe earthquakes can induce damages to Concrete Face Rockfill Dams (CFRDs) such as concrete cracking and joint's water stops distressing where high in-plane transversal normal stresses develop. Although these damages rarely jeopardize the dam safety, they cause large water reservoir leakages that hinder the dam functioning. This issue can be addressed using well know numerical methods; however, given the wide range of parameters involved, it would seem appropriate to develop a simple yet reliable procedure to get a close understanding how their interaction affects the CFRD’s overall behavior. Accordingly, once the physics of the problem is better understood one can proceed to perform a detailed design of the various components of the dam. To this end an easy-to-use procedure that accounts for the dam height effects, valley narrowness, valley slopes, width of concrete slabs and seismic excitation characteristics was developed. The procedure is the dynamic complement of a method recently developed to evaluate in-plane transversal normal stresses in the concrete face of CFRD’s due to dam reservoir filling [ ]. Using these two procedures in a sequential manner, it is possible to define the concrete slab in-plane normal stresses induced by the reservoir filling and the action of orthogonal horizontal seismic excitations acting at the same time upstream-downstream and cross river. Both procedures were developed from a data base generated using nonlinear static and dynamic three-dimensional numerical analyses on the same group of CFRD’s. Then, the results were interpreted with the Buckingham Pi theorem and various relationships were developed. In the above reference, the method to evaluate the concrete face in-plane transversal normal stresses caused by the first reservoir filling was reported. In this paper, the seismic procedure is first developed and then through an example the whole method (dam construction, reservoir filling plus seismic loading) of analysis is assessed.

关键词： CFR dams dynamic analysis in-plane normal stresses concrete face

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Effect of ultraviolet irradiation and chlorination on ampicillin-resistant

Yuchen PANG,Jingjing HUANG,Jinying XI,Hongying HU,Yun ZHU

《环境科学与工程前沿（英文）》 2016年第10卷第3期页码 522-530 doi: 10.1007/s11783-015-0779-9

摘要： Antibiotic resistance is a serious public health risk that may spread via potable and reclaimed water. Effective disinfection is important for inactivation of antibiotic-resistant bacteria and disruption of antibiotic resistance genes. Ampicillin is a widely prescribed antibiotic but its effectiveness is increasingly undermined by resistance. In this study, changes in ampicillin resistance for ( ) CGMCC 1.1595 were analyzed after exposure to different doses of ultraviolet (UV) or chlorine, and damage incurred by the plasmid encoding ampicillin resistance gene was assessed. We reported a greater stability in ampicillin-resistant CGMCC 1.1595 after UV irradiation or chlorination when compared with previously published data for other strains. UV irradiation and chlorination led to a shift in the mortality frequency distributions of ampicillin-resistant when subsequently exposed to ampicillin. The ampicillin hemi-inhibitory concentration (IC ) without disinfection was 3800 mg·L , and an increment was observed after UV irradiation or chlorination. The IC of ampicillin-resistant was 1.5-fold higher at a UV dose of 40 mJ·cm , and was 1.4-fold higher when exposed to 2.0 mg·L chlorine. These results indicate that UV irradiation and chlorination can potentially increase the risk of selection for strains with high ampicillin resistance. There was no evident damage to after 1–10 mg Cl ·L chlorination, while a UV dose of 80 mJ·cm yielded a damage ratio for of approximately 1.2-log. Therefore, high UV doses are required for effective disruption of antibiotic resistance genes in bacteria.

关键词： antibiotic resistance Escherichia coli ampicillin resistance gene ultraviolet irradiation chlorination

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Use of gamma-irradiation pretreatment for enhancement of anaerobic digestibility of sewage sludge

YUAN Shoujun, ZHENG Zheng, YU Xin, ZHAO Yongfu, MU Yanyan

《环境科学与工程前沿（英文）》 2008年第2卷第2期页码 247-250 doi: 10.1007/s11783-008-0041-9

摘要： The effects of ?-irradiation pretreatment on anaerobic digestibility of sewage sludge was investigated in this paper. Parameters like solid components, soluble components, and biogas production of anaerobic digestion experiment for sewage sludge were measured. The values of these parameters were compared before and after ?-irradiation pretreatment. Total solid (TS), volatile solid (VS), suspended solid (SS), volatile suspended solid (VSS), and average floc size of samples decreased after ?-irradiation treatment. Besides, floc size distribution of sewage sludge shifted from 80–100 ?m to 0–40 ?m after ?-irradiation treatment at the doses from 0 to 30 kGy, which indicated the disintegration of sewage sludge. Moreover, microbe cells of sewage sludge were ruptured by ?-irradiation treatment, which resulted in the release of cytoplasm and increase of soluble chemical oxygen demand (SCOD). Both sludge disintegration and microbe cells rupture enhanced the subsequent anaerobic digestion process, which was demonstrated by the increase of accumulated biogas production. Compared with digesters fed with none irradiated sludge, the accumulated biogas production increased 44, 98, and 178 mL for digesters fed sludge irradiated at 2.48, 6.51, and 11.24 kGy, respectively. The results indicated that ?-irradiation pretreatment could effectively enhance anaerobic digestibility of sewage sludge, and correspondingly, could accelerate hydrolysis process, shorten sludge retention time of sludge anaerobic digestion process.

关键词： anaerobic digestibility soluble chemical cytoplasm digestion process soluble

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论正态云模型的普适性

李德毅,刘常昱

《中国工程科学》 2004年第6卷第8期页码 28-34

摘要：

分布函数是分析随机现象的重要工具，正态分布是最重要的概率分布，在自然科学和社会科学中应用广泛；隶属函数是模糊集合的基石，正态隶属函数也有广泛的应用。但是，精确确定一个模糊概念的隶属函数已经成为模糊学应用的瓶颈。云模型把随机性和模糊性结合起来，用数字特征熵，揭示随机性与模糊性的关联性，并用来表示一个定性概念的粒度。正态云模型通过期望、熵和超熵构成的特定结构发生器，生成定性概念的定量转换值，体现概念的不确定性。这种特定结构不但放宽了形成正态分布的前提条件，而且把精确确定隶属函数放宽到构造正态隶属度分布的期望函数，因而更具有普遍适用性，更简单、直接地完成了定性与定量之间的相互转换过程。

关键词：正态分布函数隶属度正态云模型概念粒度普适性

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Additive direct-write microfabrication for MEMS: A review

Kwok Siong TEH

《机械工程前沿（英文）》 2017年第12卷第4期页码 490-509 doi: 10.1007/s11465-017-0484-4

摘要：

Direct-write additive manufacturing refers to a rich and growing repertoire of well-established fabrication techniques that builds solid objects directly from computer-generated solid models without elaborate intermediate fabrication steps. At the macroscale, direct-write techniques such as stereolithography, selective laser sintering, fused deposition modeling ink-jet printing, and laminated object manufacturing have significantly reduced concept-to-product lead time, enabled complex geometries, and importantly, has led to the renaissance in fabrication known as the . The technological premises of all direct-write additive manufacturing are identical—converting computer generated three-dimensional models into layers of two-dimensional planes or slices, which are then reconstructed sequentially into three-dimensional solid objects in a layer-by-layer format. The key differences between the various additive manufacturing techniques are the means of creating the finished layers and the ancillary processes that accompany them. While still at its infancy, direct-write additive manufacturing techniques at the microscale have the potential to significantly lower the barrier-of-entry—in terms of cost, time and training—for the prototyping and fabrication of MEMS parts that have larger dimensions, high aspect ratios, and complex shapes. In recent years, significant advancements in materials chemistry, laser technology, heat and fluid modeling, and control systems have enabled additive manufacturing to achieve higher resolutions at the micrometer and nanometer length scales to be a viable technology for MEMS fabrication. Compared to traditional MEMS processes that rely heavily on expensive equipment and time-consuming steps, direct-write additive manufacturing techniques allow for rapid design-to-prototype realization by limiting or circumventing the need for cleanrooms, photolithography and extensive training. With current direct-write additive manufacturing technologies, it is possible to fabricate unsophisticated micrometer scale structures at adequate resolutions and precisions using materials that range from polymers, metals, ceramics, to composites. In both academia and industry, direct-write additive manufacturing offers extraordinary promises to revolutionize research and development in microfabrication and MEMS technologies. Importantly, direct-write additive manufacturing could appreciably augment current MEMS fabrication technologies, enable faster design-to-product cycle, empower new paradigms in MEMS designs, and critically, encourage wider participation in MEMS research at institutions or for individuals with limited or no access to cleanroom facilities. This article aims to provide a limited review of the current landscape of direct-write additive manufacturing techniques that are potentially applicable for MEMS microfabrication.

关键词： direct-write additive manufacturing microfabrication MEMS

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正态云模型的重尾性质证明

李德毅,刘常昱,淦文燕

《中国工程科学》 2011年第13卷第4期页码 20-23

摘要：

正态分布和重尾分布在概率研究中具有非常重要的地位，二者具有完全不同的数学形式和物理意义。正态分布的密度函数以指数函数衰减至0，服从正态分布的随机变量，其绝大多数取值在其期望附近，偏离期望很大的取值很少。而服从重尾分布的随机变量，其尾分布函数具有重尾特性，密度函数以幂指数衰减至0。笔者证明了正态云模型是具有均值的重尾分布，是介于正态分布与重尾分布之间的中间状态，正态云模型的参数超熵He是可以实现正态分布向重尾分布转换的桥梁。

关键词：正态分布重尾分布正态云模型峰度

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Modeling and simulation of normal and hemiparetic gait

Lely A. LUENGAS,Esperanza CAMARGO,Giovanni SANCHEZ

《机械工程前沿（英文）》 2015年第10卷第3期页码 233-241 doi: 10.1007/s11465-015-0343-0

摘要：

Gait is the collective term for the two types of bipedal locomotion, walking and running. This paper is focused on walking. The analysis of human gait is of interest to many different disciplines, including biomechanics, human-movement science, rehabilitation and medicine in general. Here we present a new model that is capable of reproducing the properties of walking, normal and pathological. The aim of this paper is to establish the biomechanical principles that underlie human walking by using Lagrange method. The constraint forces of Rayleigh dissipation function, through which to consider the effect on the tissues in the gait, are included. Depending on the value of the factor present in the Rayleigh dissipation function, both normal and pathological gait can be simulated. First of all, we apply it in the normal gait and then in the permanent hemiparetic gait. Anthropometric data of adult person are used by simulation, and it is possible to use anthropometric data for children but is necessary to consider existing table of anthropometric data. Validation of these models includes simulations of passive dynamic gait that walk on level ground. The dynamic walking approach provides a new perspective of gait analysis, focusing on the kinematics and kinetics of gait. There have been studies and simulations to show normal human gait, but few of them have focused on abnormal, especially hemiparetic gait. Quantitative comparisons of the model predictions with gait measurements show that the model can reproduce the significant characteristics of normal gait.

关键词： bipedal gait biomechanics dynamic walking gait model human gait hemiparetic human gait

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Effects of irradiation on chromium’s behavior in ferritic/martensitic FeCr alloy

Xinfu HE, Wen YANG, Zhehao QU, Sheng FAN

《能源前沿（英文）》 2009年第3卷第2期页码 181-183 doi: 10.1007/s11708-009-0025-x

摘要： The effects of irradiation on chromium performance under different temperatures in Fe-20at%Cr were modeled by modified Marlowe code. Chromium precipitation was observed in FeCr alloy after irradiation; interstitial Chromium atoms are the preferred formation of mixed Fe-Cr dumbbells in the direction of<110>and<111>; interstitial chromium atoms congregated on {111} and {110} plane. The results are compared with experiment observations and are useful to understanding the irradiation performances of FeCr alloy.

关键词： irradiation Fe-20at%Cr alloy chromium segregation