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Improvement of the cascading closed loop cycle system

ZHANG Guoqiang, CAI Ruixian

《能源前沿（英文）》 2007年 第1卷 第3期   页码 341-346 doi: 10.1007/s11708-007-0051-5

摘要： Aspen Plus was used to simulate and get more information about the cascading closed loop cycle (CCLC) system [1–3]. Following evaluation of the variable temperature heat source (e.g. gas turbine flue gas) utilized by the CCLC, both qualitative and quantitive comparisons between the system and simple steam Rankine cycle, were made. The results indicate that CCLC has the advantage in recuperating exergy from flue gas, but it cannot sufficiently convert the recuperated exergy to useful work. To improve the utilization of low temperature flue gas heat, the properties and parameters of the working substance must match conditions of the low temperature heat source. A better cycle scheme and pressure distribution was proposed to raise the efficiency of the CCLC. In addition, the multifunction system concept was introduced to improve the performance of CCLC with solar energy.
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Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures

《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0695-1

摘要： This study presents a family of novel translational parallel mechanisms (TPMs) with single-loop topological structures. The proposed mechanism consists of only revolute and prismatic joints. The novel TPMs are simpler in structure and have fewer joints and components than the well-known Delta Robot. Four types of 2-degree of freedom driving systems are applied to different limb structures to avoid the moving actuator that causes the problem of increased moving mass. Four sample TPMs are constructed using the synthesized limbs, and one of them is investigated in terms of kinematic performance. First, a position analysis is performed and validated through numerical simulation to reveal the characteristics of partially decoupled motion, which improves the controllability of TPM. Second, singular configurations are identified, and the resulting singularity curve is obtained. Lastly, the workspace of TPM is analyzed, and the relationship between the singular configurations and the reachable workspace is explored. The workspace of the 3-CRR (C denotes the cylindrical joint and R denotes the revolute joint) translational mechanism is also presented to prove that the proposed TPM has a fairly large workspace.

关键词： translational parallel mechanism     single loop     multiple driving system     workspace analysis     singularity    

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Development of a hydrodynamic model and the corresponding virtual software for dual-loop circulating

Shanwei Hu, Xinhua Liu

《化学科学与工程前沿（英文）》 2021年 第15卷 第3期   页码 579-590 doi: 10.1007/s11705-020-1953-6

摘要： Dual-loop circulating fluidized bed (CFB) reactors have been widely applied in industry because of their good heat and mass transfer characteristics and continuous handling ability. However, the design of such reactors is notoriously difficult owing to the poor understanding of the underlying mechanisms, meaning it has been heavily based on empiricism and stepwise experiments. Modeling the gas-solid CFB system requires a quantitative description of the multiscale heterogeneity in the sub-reactors and the strong coupling between them. This article proposed a general method for modeling multi-loop CFB systems by utilizing the energy minimization multiscale (EMMS) principle. A full-loop modeling scheme was implemented by using the EMMS model and/or its extension models to compute the hydrodynamic parameters of the sub-reactors, to achieve the mass conservation and pressure balance in each circulation loop. Based on the modularization strategy, corresponding interactive simulation software was further developed to facilitate the flexible creation and fast modeling of a customized multi-loop CFB reactor. This research can be expected to provide quantitative references for the design and scale-up of gas-solid CFB reactors and lay a solid foundation for the realization of virtual process engineering.

关键词： multi-loop circulating fluidized bed     mathematical modeling     energy minimization multiscale     virtual fluidization     mesoscale structure    

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Loop theory and applications to some key problems of kinematic structure of kinematic chains

Huafeng DING, Zhen HUANG

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 276-283 doi: 10.1007/s11465-009-0061-6

摘要： Structure synthesis of mechanisms is a pivotal issue in the field of mechanical innovation and mechanical conceptual design. In this paper, a new loop theory of kinematic chains is proposed. Based on this theory, some key problems that hamper computer-based automatic synthesis of mechanisms are solved. 1) The open problem of isomorphism of kinematic chains that has lasted for more than four decades is successfully solved. 2) A new rigid sub-chain detection method that is especially suitable for complex chains is proposed. 3) The characteristic representation code remains the same even if the drawing modes and labeling ways of a chain are changed, and an atlas database of kinematic chains is established. The multi-value problem for the representation of kinematic chains is solved. The results in this paper will benefit the digitization and computerization of mechanical conceptual design.

关键词： Loop theory     kinematic chains     isomorphism     atlas database    

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UPFC setting to avoid active power flow loop considering wind power uncertainty

Shenghu LI, Ting WANG

《能源前沿（英文）》 2023年 第17卷 第1期   页码 165-175 doi: 10.1007/s11708-020-0686-z

摘要： The active power loop flow (APLF) may be caused by impropriate network configuration, impropriate parameter settings, and/or stochastic bus powers. The power flow controllers, e.g., the unified power flow controller (UPFC), may be the reason and the solution to the loop flows. In this paper, the critical existence condition of the APLF is newly integrated into the simultaneous power flow model for the system and UPFC. Compared with the existing method of alternatively solving the simultaneous power flow and sensitivity-based approaching to the critical existing condition, the integrated power flow needs less iterations and calculation time. Besides, with wind power fluctuation, the interval power flow (IPF) is introduced into the integrated power flow, and solved with the affine Krawcyzk iteration to make sure that the range of active power setting of the UPFC not yielding the APLF. Compared with Monte Carlo simulation, the IPF has the similar accuracy but less time.

关键词： active power loop flow (APLF)     unified power flow controller (UPFC)     wind power uncertainty     interval power flow (IPF)    

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Experimental investigations on operating characteristics of a closed loop pulsating heat pipe

Yu WANG

《能源前沿（英文）》 2015年 第9卷 第2期   页码 134-141 doi: 10.1007/s11708-015-0354-x

摘要： The operating mechanism of the pulsating heat pipe (PHP) is not well understood and the present technology cannot predict required design parameters for a given task. The aim of research work presented in this paper is to better understand the operation regimes of the PHP through experimental investigations. A series of experiments were conducted on a closed loop PHP with 5 turns made of copper capillary tube of 2 mm in inner diameter. Two different working fluids viz. ethanol and acetone were employed. The operating characteristics were studied for the variation of heat input, filling ratio (FR) and inclination angle of the tested device. The results strongly demonstrate the effect of the filling ratio of the working fluid on the operational stability and heat transfer capability of the device. Important insight into the operational characteristics of PHP has been obtained.

关键词： closed loop pulsating heat pipe     thermal performance     operation limit     thermography    

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combined modulated feedback and temperature compensation approach to improve bias drift of a closed-loop

Ming-jun MA,Zhong-he JIN,Hui-jie ZHU

《信息与电子工程前沿（英文）》 2015年 第16卷 第6期   页码 497-510 doi: 10.1631/FITEE.1400349

摘要： The bias drift of a micro-electro-mechanical systems (MEMS) accelerometer suffers from the 1/ noise and the temperature effect. For massive applications, the bias drift urgently needs to be improved. Conventional methods often cannot address the 1/ noise and temperature effect in one architecture. In this paper, a combined approach on closed-loop architecture modification is proposed to minimize the bias drift. The modulated feedback approach is used to isolate the 1/ noise that exists in the conventional direct feedback approach. Then a common mode signal is created and added into the closed loop on the basis of modulated feedback architecture, to compensate for the temperature drift. With the combined approach, the bias instability is improved to less than 13 μ , and the drift of the Allan variance result is reduced to 17 μ at 100 s of the integration time. The temperature coefficient is reduced from 4.68 to 0.1 m /°C. The combined approach could be useful for many other closed-loop accelerometers.

关键词： Bias drift     Closed-loop MEMS accelerometer     Modulated feedback approach     Temperature compensation    

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Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 55-65 doi: 10.1007/s11465-019-0545-y

摘要： When a fast-steering mirror (FSM) system is designed, satisfying the performance requirements before fabrication and assembly is vital. This study proposes a structural parameter design approach for an FSM system based on the quantitative analysis of the required closed-loop bandwidth. First, the open-loop transfer function of the FSM system is derived. In accordance with the transfer function, the notch filter and proportional-integral (PI) feedback controller are designed as a closed-loop controller. The gains of the PI controller are determined by maximizing the closed-loop bandwidth while ensuring the robustness of the system. Then, the two unknown variables of rotational radius and stiffness in the open-loop transfer function are optimized, considering the bandwidth as a constraint condition. Finally, the structural parameters of the stage are determined on the basis of the optimized results of rotational radius and stiffness. Simulations are conducted to verify the theoretical analysis. A prototype of the FSM system is fabricated, and corresponding experimental tests are conducted. Experimental results indicate that the bandwidth of the proposed FSM system is 117.6 Hz, which satisfies the minimum bandwidth requirement of 100 Hz.

关键词： fast-steering mirror     structural parameter     PI controller     bandwidth     notch filter    

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quantification of 3′-terminal 2′-O-methylated small RNAs by utilizing oxidative deep sequencing and stem-loop

《医学前沿（英文）》 2022年 第16卷 第2期   页码 240-250 doi: 10.1007/s11684-021-0909-7

摘要： The continuing discoveries of novel classes of RNA modifications in various organisms have raised the need for improving sensitive, convenient, and reliable methods for quantifying RNA modifications. In particular, a subset of small RNAs, including microRNAs (miRNAs) and Piwi-interacting RNAs (piRNAs), are modified at their 3′-terminal nucleotides via 2′-O-methylation. However, quantifying the levels of these small RNAs is difficult because 2′-O-methylation at the RNA 3′-terminus inhibits the activity of polyadenylate polymerase and T4 RNA ligase. These two enzymes are indispensable for RNA labeling or ligation in conventional miRNA quantification assays. In this study, we profiled 3′-terminal 2′-O-methyl plant miRNAs in the livers of rice-fed mice by oxidative deep sequencing and detected increasing amounts of plant miRNAs with prolonged oxidation treatment. We further compared the efficiency of stem-loop and poly(A)-tailed RT-qPCR in quantifying plant miRNAs in animal tissues and identified stem-loop RT-qPCR as the only suitable approach. Likewise, stem-loop RT-qPCR was superior to poly(A)-tailed RT-qPCR in quantifying 3′-terminal 2′-O-methyl piRNAs in human seminal plasma. In summary, this study established a standard procedure for quantifying the levels of 3′-terminal 2′-O-methyl miRNAs in plants and piRNAs. Accurate measurement of the 3′-terminal 2′-O-methylation of small RNAs has profound implications for understanding their pathophysiologic roles in biological systems.

关键词： small RNAs     2′-O-methylation     sequencing     RT-qPCR    

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Simulation of long-term nutrient removal in a full-scale closed-loop bioreactor for sewage treatment:

Zheng LI,Rong QI,Wei AN,Takashi MINO,Tadashi SHOJI,Willy VERSTRAETE,Jian GU,Shengtao LI,Shiwei XU,Min YANG

《环境科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 534-544 doi: 10.1007/s11783-014-0660-2

摘要： In this study, the performance of nitrogen and phosphorus removal in a full-scale closed-loop bioreactor (oxidation ditch) system was simulated using the ASM2d model. Routine data describing the process for two years were compiled for calibration and validation. To overcome the identifiability problem, the classic Bayesian inference approach was utilized for parameter estimation. The calibrated model could describe the long-term trend of nutrient removal and short-term variations of the process performance, showing that the Bayesian method was a reliable and useful tool for the parameter estimation of the activated sludge models. The anoxic phosphate uptake by polyphosphate accumulating organisms (PAO) contributed 71.2% of the total Poly-P storage, which reveals the dominance of denitrifying phosphorus removal process under the oxygen limiting conditions. It was found that 58.7% of the anoxic Poly-P storage and denitrification by PAO in the reactor was achieved in the aerated compartment, implying that the PAO’s anoxic activity was significantly stimulated by the low dissolved oxygen (DO) level in this compartment due to the oxygen gradient caused by brush aerator.

关键词： activated sludge model     Bayesian inference     biological nutrient removal     closed-loop bioreactor     oxidation ditch     denitrifying polyphosphate accumulating organisms    

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system for industrial robots: A CPS-based hybrid architecture for smart assembly shop floors with closed-loop

Qingmeng TAN, Yifei TONG, Shaofeng WU, Dongbo LI

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 1-11 doi: 10.1007/s11465-019-0563-9

摘要： Given the multiple varieties and small batches, the production of industrial robots faces the ongoing challenges of flexibility, self-organization, self-configuration, and other “smart” requirements. Recently, cyber physical systems have provided a promising solution for the requirements mentioned above. Despite recent progress, some critical issues have not been fully addressed at the shop floor level, including dynamic reorganization and reconfiguration, ubiquitous networking, and time constrained computing. Toward the next generation production system for industrial robots, this study proposed a hybrid architecture for smart assembly shop floors with closed-loop dynamic cyber physical interactions. Aiming for dynamic reorganization and reconfiguration, the study also proposed modularized smart assembly units for the deployment of physical assembly processes. Enabling technologies, such as multiagent system (MAS), self-organized wireless sensor actuator networks, and edge computing, were discussed and then integrated into the proposed architecture. Furthermore, a multijoint robot assembly process was selected as a target scenario. Thus, an MAS was developed to simulate the coordination and negotiation mechanisms for the proposed architecture on the basis of the Java Agent Development Framework platform.

关键词： cyber physical system     robot assembly     multiagent system     architecture    

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Pricing and production strategies in remanufacturing from the perspectives of supply chain: Review and future directions

《工程管理前沿（英文）》 doi: 10.1007/s42524-023-0251-7

摘要： Remanufacturing is widely recognized as beneficial to the environment and a circular economy. However, remanufacturing is more complex than traditional manufacturing due to the effects of government policy, uncertainty of consumer preferences, competition and cooperation among firms, and so on. These factors motivate academics to optimize remanufacturing outcomes, especially for product pricing and production. This study reviews the published literature on pricing and production strategies in remanufacturing from four perspectives of supply chain, namely, government policy, consumer characteristics, relationships among firms, and supply chain structures. Review results can benefit scholars/practitioners in the future by highlighting the challenges and opportunities in remanufacturing strategies.

关键词： remanufacturing     reverse and closed-loop supply chain     circular economy    

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The Integration Model of Closed-Loop Supply Chain Resource Allocation Considering Remanufacturing

Xiao-qiu Shi,Yan-yan Li,Wei Long

《工程管理前沿（英文）》 2016年 第3卷 第2期   页码 132-135 doi: 10.15302/J-FEM-2016026

摘要： Logistics resource planning is an integration model of materials requirement planning and distribution resource planning which is a resource allocation technology. It is a technology of satisfying both production material supply and resource allocation optimization which is based on inventory management. For the remanufacturing supply chain, recycling and rebuilding of products form a reverse materials movement loop which challenges the traditional logistics resource planning system. For the characteristics of reverse logistics of remanufacturing supply chain, we propose a closed-loop supply chain resource allocation model based on autonomous multi-entity. We focus on integration resource allocation model of materials requirement planning and distribution resource planning considering remanufacturing.

关键词： remanufacturing     supply chain     reverse logistics     resource allocation     integration model    

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Digitalization optical open loop test system for fiber optic gyroscope

ZHANG Deng-wei, SHU Xiao-wu, MU Xu-dong, LIU Cheng

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 434-438 doi: 10.1007/s11465-006-0053-8

摘要： In order to receive and process the open loop signal from fiber optic gyroscopes speedily, stably and expediently, and to realize the amity interface between human and machine, a digital system that can convert GPIB (general purpose interface bus ) parallel bus into Universal Serial Bus is developed. All the interface functions of GPIB and the hardware system are realized through FPGA. With a digital sampling and processing system designed with VC++ in Windows platform, the real-time controlling procedure, high-speed receiving and sending data can be carried out, and the results can be displayed too. So the design of the system is flexible, the reliability and the stability are improved, error rate is no more than 10, the highest bit rate is 8 MB/s and the open loop detection system for optic fiber gyros achieves standardization and complete digitalization simultaneously.

关键词： stability     real-time controlling     standardization     controlling procedure     complete digitalization    

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Parametric study on seismic performance of self-centering reinforced concrete column with bottom-placed rubber layer

《结构与土木工程前沿（英文）》   页码 1145-1162 doi: 10.1007/s11709-023-0945-2

摘要： To realize seismic-resilient reinforced concrete (RC) moment-resisting frame structures, a novel self-centering RC column with a rubber layer placed at the bottom (SRRC column) is proposed herein. For the column, the longitudinal reinforcement dissipates seismic energy, the rubber layer allows the rocking of the column, and the unbonded prestressed tendon enables self-centering capacity. A refined finite element model of the SRRC column is developed, the effectiveness of which is validated based on experimental results. Results show that the SRRC column exhibits stable energy dissipation capacity and no strength degradation; additionally, it can significantly reduce permanent residual deformation and mitigate damage to concrete. Extensive parametric studies pertaining to SRRC columns have been conducted to investigate the critical factors affecting their seismic performance.

关键词： seismic resilience     self-centering     rubber layer     flag-shaped hysteresis loop     parametric study    

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标题 作者 时间 类型 操作

Improvement of the cascading closed loop cycle system

ZHANG Guoqiang, CAI Ruixian

期刊论文

Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures

期刊论文

Development of a hydrodynamic model and the corresponding virtual software for dual-loop circulating

Shanwei Hu, Xinhua Liu

期刊论文

Loop theory and applications to some key problems of kinematic structure of kinematic chains

Huafeng DING, Zhen HUANG

期刊论文

UPFC setting to avoid active power flow loop considering wind power uncertainty

Shenghu LI, Ting WANG

期刊论文

Experimental investigations on operating characteristics of a closed loop pulsating heat pipe

Yu WANG

期刊论文

combined modulated feedback and temperature compensation approach to improve bias drift of a closed-loop

Ming-jun MA,Zhong-he JIN,Hui-jie ZHU

期刊论文

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

期刊论文

quantification of 3′-terminal 2′-O-methylated small RNAs by utilizing oxidative deep sequencing and stem-loop

期刊论文

Simulation of long-term nutrient removal in a full-scale closed-loop bioreactor for sewage treatment:

Zheng LI,Rong QI,Wei AN,Takashi MINO,Tadashi SHOJI,Willy VERSTRAETE,Jian GU,Shengtao LI,Shiwei XU,Min YANG

期刊论文

system for industrial robots: A CPS-based hybrid architecture for smart assembly shop floors with closed-loop

Qingmeng TAN, Yifei TONG, Shaofeng WU, Dongbo LI

期刊论文

Pricing and production strategies in remanufacturing from the perspectives of supply chain: Review and future directions

期刊论文

The Integration Model of Closed-Loop Supply Chain Resource Allocation Considering Remanufacturing

Xiao-qiu Shi,Yan-yan Li,Wei Long

期刊论文

Digitalization optical open loop test system for fiber optic gyroscope

ZHANG Deng-wei, SHU Xiao-wu, MU Xu-dong, LIU Cheng

期刊论文

Parametric study on seismic performance of self-centering reinforced concrete column with bottom-placed rubber layer

期刊论文