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Impact of selection of DC base values and DC link control strategies on sequential AC-DC power-flow convergence

Shagufta KHAN,Suman BHOWMICK

《能源前沿(英文)》 2015年 第9卷 第4期   页码 399-412 doi: 10.1007/s11708-015-0374-6

摘要: This paper demonstrates the convergence of the integrated AC-DC power-flow algorithm as affected by the selection of different base values for the DC quantities and adoption of different control strategies for the DC link. For power-flow modeling of integrated AC-DC systems, the base values of the various DC quantities can be defined in several ways, giving rise to different sets of per-unit system equations. It is observed that different per-unit system models affect the convergence of the power-flow algorithm differently. In a similar manner, the control strategy adopted for the DC link also affects the power-flow convergence. The sequential method is used to solve the DC variables in the Newton Raphson (NR) power flow model, where AC and DC systems are solved separately and are coupled by injecting an equivalent amount of real and reactive power at the terminal AC buses. Now, for a majority of the possible control strategies, the equivalent real and reactive power injections at the concerned buses can be computed a-priori and are independent of the NR iterative loop. However, for a few of the control strategies, the equivalent reactive power injections cannot be computed a-priori and need to be computed in every NR iteration. This affects the performance of the iterative process. Two different per-unit system models and six typical control strategies are taken into consideration. This is validated by numerous case studies conducted on the IEEE 118-bus and 300-bus test systems.

关键词: AC-DC power-flow     Newton-Raphson method     high voltage direct current (HVDC) control strategy    

Control strategies for disinfection byproducts by ion exchange resin, nanofiltration and their sequential

《环境科学与工程前沿(英文)》 2023年 第17卷 第10期 doi: 10.1007/s11783-023-1725-x

摘要:

● Effects of AER adsorption and NF on DBP precursors, DBPs, and TOX were examined.

关键词: Disinfection byproducts     Control     Anion exchange resin     Nanofiltration     Cytotoxicity    

mechanisms of diphenylarsinic acid on natural magnetite and siderite: Evidence from sorption kinetics, sequential

《环境科学与工程前沿(英文)》 2022年 第16卷 第9期 doi: 10.1007/s11783-022-1547-2

摘要:

• DPAA sorption followed pseudo-secondary and intra-particle diffusion models.

关键词: Diphenylarsinic acid (DPAA)     Sorption     Magnetite     Siderite     Sequential extraction     EXAFS    

Multidisciplinary co-design optimization of structural and control parameters for bucket wheel reclaimer

Yongliang YUAN, Liye LV, Shuo WANG, Xueguan SONG

《机械工程前沿(英文)》 2020年 第15卷 第3期   页码 406-416 doi: 10.1007/s11465-019-0578-2

摘要: Bucket wheel reclaimer (BWR) is an extremely complex engineering machine that involves multiple disciplines, such as structure, dynamics, and electromechanics. The conventional design strategy, namely, sequential strategy, is structural design followed by control optimization. However, the global optimal solution is difficult to achieve because of the discoordination of structural and control parameters. The co-design strategy is explored to address the aforementioned problem by combining the structural and control system design based on simultaneous dynamic optimization approach. The radial basis function model is applied for the planning of the rotation speed considering the relationships of subsystems to minimize the energy consumption per volume. Co-design strategy is implemented to resolve the optimization problem, and numerical results are compared with those of sequential strategy. The dynamic response of the BWR is also analyzed with different optimization strategies to evaluate the advantages of the strategies. Results indicate that co-design strategy not only can reduce the energy consumption of the BWR but also can achieve a smaller vibration amplitude than the sequential strategy.

关键词: bucket wheel reclaimer     co-design     energy-minimum optimization     sequential strategy    

A “Sequential Design of Simulations” approach for exploiting and calibrating discrete element simulations

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 874-885 doi: 10.1007/s11705-021-2131-1

摘要: The flow behaviours of cohesive particles in the ring shear test were simulated and examined using discrete element method guided by a design of experiments methodology. A full factorial design was used as a screening design to reveal the effects of material properties of partcles. An augmented design extending the screening design to a response surface design was constructed to establish the relations between macroscopic shear stresses and particle properties. It is found that the powder flow in the shear cell can be classified into four regimes. Shear stress is found to be sensitive to particle friction coefficient, surface energy and Young’s modulus. A considerable fluctuation of shear stress is observed in high friction and low cohesion regime. In high cohesion regime, Young’s modulus appears to have a more significant effect on the shear stress at the point of incipient flow than the shear stress during the pre-shear process. The predictions from response surface designs were validated and compared with shear stresses measured from the Schulze ring shear test. It is found that simulations and experiments showed excellent agreement under a variety of consolidation conditions, which verifies the advantages and feasibility of using the proposed “Sequential Design of Simulations” approach.

关键词: discrete element method     cohesive materials     parameter calibration     ring shear cell     design of experiments    

Comparison of sequential with intimate coupling of photolysis and biodegradation for benzotriazole

Shunan Shan, Yuting Zhang, Yining Zhang, Lanjun Hui, Wen Shi, Yongming Zhang, Bruce E. Rittmann

《环境科学与工程前沿(英文)》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0953-3

摘要: Benzotriazole (BTA) is an emerging contaminant that also is a recalcitrant compound. Sequential and intimate coupling of UV-photolysis with biodegradation were investigated for their impacts on BTA removal and mineralization in aerobic batch experiments. Special attention was given to the role of its main photolytic products, which were aminophenol (AP), formic acid (FA), maleic acid (MA), and phenazine (PHZ). Experiments with sequential coupling showed that BTA biodegradation was accelerated by photolytic pretreatment up to 9 min, but BTA biodegradation was slowed with longer photolysis. FA and MA accelerated BTA biodegradation by being labile electron-donor substrates, but AP and PHZ slowed the rate because of inhibition due to their competition for intracellular electron donor. Because more AP and PHZ accumulated with increasing photolysis time, their inhibitory effects began to dominate with longer photolysis time. Intimately coupling photolysis with biodegradation relieved the inhibition effect, because AP and PHZ were quickly biodegraded and did not accumulate, which accentuated the beneficial effect of FA and MA.

关键词: Benzotriazole     Photolysis     Biodegradation     Inhibition     Electron donor    

Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Jie Gao, Zhikai Li, Mei Dong, Weibin Fan, Jianguo Wang

《化学科学与工程前沿(英文)》 2020年 第14卷 第5期   页码 847-856 doi: 10.1007/s11705-019-1848-6

摘要: Coal-based ethanol production by hydration of ethylene is limited by the low equilibrium ethylene conversion at elevated temperature. To improve ethylene conversion, coupling hydration of ethylene with a potential ethanol consumption reaction was analyzed thermodynamically. Five reactions have been attempted and compared: (1) dehydration of ethanol to ethyl ether ( ), (2) dehydrogenation of ethanol to acetaldehyde ( ), (3) esterification of acetic acid with ethanol ( ), (4) dehydrogenation of ethanol to ethyl acetate ( ), and (5) oxidative dehydrogenation of ethanol to ethyl acetate ( ). The equilibrium constants and equilibrium distributions of the coupled reactions were calculated and the effects of feed composition, temperature and pressure upon the ethylene equilibrium conversion were examined. The results show that dehydrogenation of ethanol to acetaldehyde has little effect on ethylene conversion, whereas for dehydrogenation of ethanol to acetaldehyde and ethyl acetate, ethylene conversion can be improved from 8% to 12.8% and 18.5%, respectively, under conditions of H O/C H = 2, 10 atm and 300°C. The esterification of acetic acid with ethanol can greatly enhance the ethylene conversion to 22.5%; in particular, ethylene can be actually completely converted to ethyl acetate by coupling oxidative dehydrogenation of ethanol.

关键词: ethylene     ethanol     thermodynamics     coupling    

Successful management of seven cases of critical COVID-19 with early noninvasive–invasive sequential

Mian Peng, Xueyan Liu, Jinxiu Li, Di Ren, Yongfeng Liu, Xi Meng, Yansi Lyu, Ronglin Chen, Baojun Yu, Weixiong Zhong

《医学前沿(英文)》 2020年 第14卷 第5期   页码 674-680 doi: 10.1007/s11684-020-0796-3

摘要: We report the clinical and laboratory findings and successful management of seven patients with critical coronavirus disease 2019 (COVID-19) requiring mechanical ventilation (MV). The patients were diagnosed based on epidemiological history, clinical manifestations, and nucleic acid testing. Upon diagnosis with COVID-19 of critical severity, the patients were admitted to the intensive care unit, where they received early noninvasive–invasive sequential ventilation, early prone positioning, and bundle pharmacotherapy regimen, which consists of antiviral, anti-inflammation, immune-enhancing, and complication-prophylaxis medicines. The patients presented fever ( = 7, 100%), dry cough ( = 3, 42.9%), weakness ( = 2, 28.6%), chest tightness ( = 1, 14.3%), and/or muscle pain ( = 1, 14.3%). All patients had normal or lower than normal white blood cell count/lymphocyte count, and chest computed tomography scans showed bilateral patchy shadows or ground glass opacity in the lungs. Nucleic acid testing confirmed COVID-19 in all seven patients. The median MV duration and intensive care unit stay were 9.9 days (interquartile range, 6.5–14.6 days; range, 5–17 days) and 12.9 days (interquartile range, 9.7–17.6 days; range, 7–19 days), respectively. All seven patients were extubated, weaned off MV, transferred to the common ward, and discharged as of the writing of this report. Thus, we concluded that good outcomes for patients with critical COVID-19 can be achieved with early noninvasive–invasive sequential ventilation and bundle pharmacotherapy.

关键词: COVID-19     noninvasive–invasive sequential ventilation     bundle pharmacotherapy    

基于深度序列特征学习的临床感染性角膜炎图像分类 Article

许叶圣, 孔鸣, 谢文加, 段润平, 方钲清, 林宇萧, 朱强, 汤斯亮, 吴飞, 姚玉峰

《工程(英文)》 2021年 第7卷 第7期   页码 1002-1010 doi: 10.1016/j.eng.2020.04.012

摘要:

感染性角膜炎是最常见的角膜疾病之一,病原体在角膜中生长引发炎症反应并损伤角膜组织。感染性角膜炎作为一种临床急症,需要快速、精准的诊断,确保患者能够得到及时、准确的治疗,从而遏制疾病的发展,并将其对角膜的损伤降到最低。否则患者会有失明的风险,严重者甚至会失去眼球。本文提出了一种深度序列特征学习模型,该模型能够通过对临床图像的分类高效地鉴别不同的感染性角膜炎。我们针对感染性角膜炎的特点设计了一种能够解耦临床图像中最具区别
性的特征并保持其空间结构的机制。通过比较,我们提出的深度序列特征学习模型在120张图像的测试集上的准确率能够达到80%,远高于421位眼科医生所能达到的平均水平[(49.27 ± 11.5)]%。

 

关键词: 深度学习     角膜病     序列特征     机器学习     长短时记忆    

流体电化学靶向诱生硫酸根自由基降解水中微污染物 Article

郑文天, 尤世界, 姚远, 任南琪, 丁彬, 李方, 刘艳彪

《工程(英文)》 2023年 第30卷 第11期   页码 144-152 doi: 10.1016/j.eng.2022.12.005

摘要:

水中微污染物的深度去除是环境工程领域的重大挑战。受限于低浓度和高毒性等污染特征,传统水处理策略难以实现这类污染物的有效去除。基于此,本文提出了流体电化学靶向诱生硫酸根自由基(SO4•–)的研究设想,通过构筑穿透式电化学反应系统,实现了阳极将硫酸根离子(SO42−)氧化生成过硫酸根(S2O82−),再通过阴极还原反应将S2O82−转化为SO4•–。开展了流体电化学系统构造原理、硫酸根自由基靶向生成机制和微污染物降解机理等相关研究。结果表明,在最优实验条件下,该系统可在单次流模式下实现苯胺的高效降解(100%)和总有机碳的有效去除(65.0%)。该系统在宽pH范围内和复杂水基质条件下均能实现多种微污染物的有效去除。本工作基于“以废治废”理念,结合了膜分离和电化学的技术优势,有望为水中微污染物的深度去除提供一种潜在可行的技术选择。

关键词: 高级氧化     链式反应     硫酸根离子     微污染物     顺序电化学体系    

Removal of pharmaceutical and personal care products by sequential ultraviolet and ozonation process

Qian SUI, Jun HUANG, Shuguang LU, Shubo DENG, Bin WANG, Wentao ZHAO, Zhaofu QIU, Gang YU

《环境科学与工程前沿(英文)》 2014年 第8卷 第1期   页码 62-68 doi: 10.1007/s11783-013-0518-z

摘要: The application of appropriate advanced treatment process in the municipal wastewater treatment plants (WWTPs) has become an important issue considering the elimination of emerging contaminants, such as pharmaceutical and personal care products (PPCPs). In the present study, the removal of 13 PPCPs belonging to different therapeutic classes by the sequential ultraviolet (UV) and ozonation process in a full-scale WWTP in Beijing was investigated over the course of ten months. Most of the target PPCPs were effectively removed, and the median removal efficiencies of individual PPCPs, ranging from -13% to 89%, were dependent on their reaction rate constants with molecular ozone. Noticeable fluctuation in the removal efficiencies of the same PPCPs was observed in different sampling campaigns. Nevertheless, the sequential UV and ozonation process still made a significant contribution to the total elimination of most PPCPs in the full-scale WWTP, by compensating for the poor or fluctuant removal performance of PPCPs by biologic treatment process.

关键词: PPCPs     advanced treatment     ozone     fluctuation     removal contribution    

免疫进化机制及其在时序模式挖掘中的应用研究

杨炳儒,秦奕青,宋泽锋

《中国工程科学》 2008年 第10卷 第4期   页码 84-89

摘要:

针对目前动态数据挖掘中存在的问题,提出基于数据增量的动态挖掘进程概念;在动态挖掘进程和生物免疫进化过程的相似性基础上,提出了知识发现中的免疫进化机制的基本内涵;给出了基于免疫进化机制的时序模式挖掘算法及其实验分析,以验证理论的正确性和有效性。

关键词: 动态数据挖掘     免疫算法     动态挖掘进程     免疫进化机制     时序模式挖掘    

Using ultrasound to improve the sequential post-synthesis modification method for making mesoporous Y

Rongxin Zhang, Peinan Zhong, Hamidreza Arandiyan, Yanan Guan, Jinmin Liu, Na Wang, Yilai Jiao, Xiaolei Fan

《化学科学与工程前沿(英文)》 2020年 第14卷 第2期   页码 275-287 doi: 10.1007/s11705-019-1905-1

摘要: Mesoporous Y zeolites were prepared by the sequential chemical dealumination (using chelating agents such as ethylenediaminetetraacetic acid, H EDTA, and citric acid aqueous solutions) and alkaline desilication (using sodium hydroxide, NaOH, aqueous solutions) treatments. Specifically, the ultrasound-assisted alkaline treatment (i.e., ultrasonic treatment) was proposed as the alternative to conventional alkaline treatments which are performed under hydrothermal conditions. In comparison with the hydrothermal alkaline treatment, the ultrasonic treatment showed the comparatively enhanced efficiency (with the reduced treatment time, i.e., 5 min vs. 30 min, all with 0.2 mol·L NaOH at 65°C) in treating the dealuminated Y zeolites for creating mesoporosity. For example, after the treatment of a dealuminated zeolite Y (using 0.1 mol·L H EDTA at 100°C for 6 h), the ultrasonic treatment produced the mesoporous zeolite Y with the specific external surface area ( ) of 160 m ·g and mesopore volume ( ) of 0.22 cm ·g , being slightly higher than that by the conventional method (i.e., = 128 m ·g and = 0.19 cm ·g ). The acidic property and catalytic activity (in catalytic cracking of -octane) of mesoporous Y zeolites obtained by the two methods were comparable. The ultrasonic desilication treatment was found to be generic, also being effective to treat the dealuminated Y zeolites by citric acid. Additionally, the first step of chemical dealumination treatment was crucial to enable the effective creation of mesopores in the parent Y zeolite (with a silicon-to-aluminium ratio, Si/Al= 2.6) regardless of the subsequent alkaline desilication treatment (i.e., ultrasonic or hydrothermal). Therefore, appropriate selection of the condition of the chemical dealumination treatment based on the property of parent zeolites, such as Si/Al ratio and crystallinity, is important for making mesoporous zeolites effectively.

关键词: zeolite Y     mesoporous zeolite     post-synthesis treatment     ultrasound     chemical dealumination treatment     alkaline desilication treatment    

Sequential degradation-based burn-in test with multiple periodic inspections

《工程管理前沿(英文)》 2021年 第8卷 第4期   页码 519-530 doi: 10.1007/s42524-021-0166-0

摘要: Burn-in has been proven effective in identifying and removing defective products before they are delivered to customers. Most existing burn-in models adopt a one-shot scheme, which may not be sufficient enough for identification. Borrowing the idea from sequential inspections for remaining useful life prediction and accelerated lifetime test, this study proposes a sequential degradation-based burn-in model with multiple periodic inspections. At each inspection epoch, the posterior probability that a product belongs to a normal one is updated with the inspected degradation level. Based on the degradation level and the updated posterior probability, a product can be disposed, put into field use, or kept in the test till the next inspection epoch. We cast the problem into a partially observed Markov decision process to minimize the expected total burn-in cost of a product, and derive some interesting structures of the optimal policy. Then, algorithms are provided to find the joint optimal inspection period and number of inspections in steps. A numerical study is also provided to illustrate the effectiveness of our proposed model.

关键词: burn-in     degradation     multiple inspections     Wiener process     partially observed Markov decision process    

Comparison of analytical procedures for measuring phosphorus content of animal manures in China

null

《农业科学与工程前沿(英文)》 2019年 第6卷 第4期   页码 431-440 doi: 10.15302/J-FASE-2019279

摘要:

The concentration and components of manure phosphorus (P) are key factors determining potential P bioavailability and runoff. The distribution of P forms in swine, poultry and cattle manures collected from intensive and extensive production systems in several areas of China was investigated with sequential fractionation and a simplified two-step (NaHCO -NaOH/EDTA) procedures. The mean total P concentration, determined by the sequential fractionation procedure of intensive swine, poultry and cattle manure, expressed as g·kg , was 14.9, 13.4 and 5.8 g·kg , respectively, and 4.4 g·kg in extensive cattle manure. In intensive swine, poultry and cattle manure about 73%, 74% and 79% of total P, respectively, was bioavailable (i.e., P extracted by H O and NaHCO ) and 78% in extensive cattle manure. The results indicated the relative environmental risk, from high to low, of swine, poultry and cattle manure. There is considerable regional variation in animal manure P across China, which needs to be considered when developing manure management strategies.

关键词: diet phosphorus     manure phosphorus     sequential P fractionation    

标题 作者 时间 类型 操作

Impact of selection of DC base values and DC link control strategies on sequential AC-DC power-flow convergence

Shagufta KHAN,Suman BHOWMICK

期刊论文

Control strategies for disinfection byproducts by ion exchange resin, nanofiltration and their sequential

期刊论文

mechanisms of diphenylarsinic acid on natural magnetite and siderite: Evidence from sorption kinetics, sequential

期刊论文

Multidisciplinary co-design optimization of structural and control parameters for bucket wheel reclaimer

Yongliang YUAN, Liye LV, Shuo WANG, Xueguan SONG

期刊论文

A “Sequential Design of Simulations” approach for exploiting and calibrating discrete element simulations

期刊论文

Comparison of sequential with intimate coupling of photolysis and biodegradation for benzotriazole

Shunan Shan, Yuting Zhang, Yining Zhang, Lanjun Hui, Wen Shi, Yongming Zhang, Bruce E. Rittmann

期刊论文

Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Jie Gao, Zhikai Li, Mei Dong, Weibin Fan, Jianguo Wang

期刊论文

Successful management of seven cases of critical COVID-19 with early noninvasive–invasive sequential

Mian Peng, Xueyan Liu, Jinxiu Li, Di Ren, Yongfeng Liu, Xi Meng, Yansi Lyu, Ronglin Chen, Baojun Yu, Weixiong Zhong

期刊论文

基于深度序列特征学习的临床感染性角膜炎图像分类

许叶圣, 孔鸣, 谢文加, 段润平, 方钲清, 林宇萧, 朱强, 汤斯亮, 吴飞, 姚玉峰

期刊论文

流体电化学靶向诱生硫酸根自由基降解水中微污染物

郑文天, 尤世界, 姚远, 任南琪, 丁彬, 李方, 刘艳彪

期刊论文

Removal of pharmaceutical and personal care products by sequential ultraviolet and ozonation process

Qian SUI, Jun HUANG, Shuguang LU, Shubo DENG, Bin WANG, Wentao ZHAO, Zhaofu QIU, Gang YU

期刊论文

免疫进化机制及其在时序模式挖掘中的应用研究

杨炳儒,秦奕青,宋泽锋

期刊论文

Using ultrasound to improve the sequential post-synthesis modification method for making mesoporous Y

Rongxin Zhang, Peinan Zhong, Hamidreza Arandiyan, Yanan Guan, Jinmin Liu, Na Wang, Yilai Jiao, Xiaolei Fan

期刊论文

Sequential degradation-based burn-in test with multiple periodic inspections

期刊论文

Comparison of analytical procedures for measuring phosphorus content of animal manures in China

null

期刊论文