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Balancing method without trial weights for rotor systems based on similitude scale model

Ruiduo YE, Liping WANG, Xiaojie HOU, Zhong LUO, Qingkai HAN

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 571-580 doi: 10.1007/s11465-018-0478-x

摘要：

A balancing method without trial weights based on the dynamic similitude scale model was proposed as a solution to the balancing problem of a large-scale rotor system. This method could be used to directly obtain the required coefficients for the balancing problem of the prototype system through a similarity model test without a prototype test. Thus, the weight test process of the prototype system was effectively eliminated in the proposed balancing method. First, with the rotor system as the research object, the analytical expression of the influence coefficient was derived on the basis of rotor dynamics theory. Then, through calculation and dimensional analysis methods, the similitude relationships of the rotor system and the influence coefficient were deduced on the basis of dynamic similitude theory. The correctness of the proposed similitude relationships was verified through numerical simulation and experiment. The balancing method without trial weights was proposed based on the similitude relationship of the influence coefficient. The effect of the balancing method without trial weights was compared with that of the traditional influence coefficient method through numerical simulation, and the results verified the correctness and effectiveness of the proposed balancing method. The results of this study provide theoretical supplements for the balancing method and the similitude design of the rotor system.

关键词： rotor system     dynamic similitude     balancing     without trial weights     influence coefficient    

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Negative weights in network time model

Zoltán A. VATTAI, Levente MÁLYUSZ

《工程管理前沿（英文）》 2022年 第9卷 第2期   页码 268-280 doi: 10.1007/s42524-020-0109-1

摘要： Time does not go backward. A negative duration, such as “time period” at first sight is difficult to interpret. Previous network techniques (CPM/PERT/PDM) did not support negative parameters and/or loops (potentially necessitating recursive calculations) in the model because of the limited computing and data storage capabilities of early computers. Monsieur Roy and John Fondahl implicitly introduced negative weights into network techniques to represent activities with fixed or estimated durations (MPM/PDM). Subsequently, the introduction of negative lead and/or lag times by software developers (IBM) apparently overcome the limitation of not allowing negative time parameters in time model. Referring to general digraph (Event on Node) representation where activities are represented by pairs of nodes and pairwise relative time restrictions are represented by weighted arrows, we can release most restraints in constructing the graph structure (incorporating the dynamic model of the inner logic of time plan), and a surprisingly flexible and handy network model can be developed that provides all the advantages of the abovementioned techniques. This paper aims to review the theoretical possibilities and technical interpretations (and use) of negative weights in network time models and discuss approximately 20 types of time-based restrictions among the activities of construction projects. We focus on pure relative time models, without considering other restrictions (such as calendar data, time-cost trade-off, resource allocation or other constraints).

关键词： graph technique     network technique     construction management     scheduling    

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Development of oxide dispersion strengthened ferritic steels with and without aluminum

Jae Hoon LEE

《能源前沿（英文）》 2012年 第6卷 第1期   页码 29-34 doi: 10.1007/s11708-012-0178-x

摘要： Pure Fe, Cr, Al, Ti elemental powders and pre-alloyed Y O powder were processed by high energy mechanical milling. The compositions of the mixed powders are designed as Fe-18Cr-0.2Ti-0.35Y O and Fe-18Cr-5Al-0.2Ti-0.35Y O in weight percent. The as-milled powders were consolidated by hot extrusion at 1423 K. The dispersed oxide particles were identified to be titania+ yttria for Al-free oxide dispersion strengthened (ODS) steel and alumina+ yttria for Al-added ODS steel, respectively. The ultimate tensile strength of Al-free ODS steel was higher than that of Al-added ODS steel over the temperature range of 298–973 K, because of the difference in number density and size of thermally stable oxide particles dispersed in both steel matrices. The strength in the longitudinal direction was lower than that in the transverse direction, probably due to anisotropy of the microstructure with elongated grains in the hot-extrusion direction for the 18%Cr-ODS steels with and without 5%Al.

关键词： oxide dispersion strengthened (ODS) steel     milling     extrusion     aluminum     yttria    

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Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 441-447 doi: 10.1007/s11709-015-0319-5

摘要： This is the first manuscript presenting an extended meshfree method for thermo- elastic fracture which does not exploit a crack tip enrichment. The crack is modeled by partition of unity enrichment of the displacement and temperature field. Only a step function is employed that facilitates the implementation. To ensure that crack tip is at the correct position, a Lagrange multiplier field ahead of the crack tip is introduced along a line. The Lagrange multiplier nodal parameters are discretised with the available meshfree functions. Two benchmark examples illustrate the efficiency of the method.

关键词： meshfree method     thermo-elasticity    

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Trial design of arch bridge of composite box section with steel web-concrete flange

Jiangang WEI, Qingwei HUANG, Baochun CHEN,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 370-375 doi: 10.1007/s11709-010-0073-7

摘要： The concrete arch bridge is a natural and appropriate structural solution, aesthetically pleasing and easily integrated into the environment, especially in mountainous and island areas. However, construction difficulty and cost will increase with heavy self-weight when the span enlarges. A potential solution is to use a composite box arch ring with steel web-concrete flange. Taking Wanzhou Yangtze River Bridge (the longest concrete arch bridge in the world with a main span of 420 m) as a prototype, trial designs of a composite box arch with steel webs (including corrugated steel webs and plain steel webs) and concrete flanges were carried out. Comparison of quantities and structural behaviors of the prototype concrete arch with the two trial designed composite arch was presented. It is shown that the self-weight of the composite arch can reduce about 28% and the structures can meet the design requirements, therefore it is possible to use the two composite arches in long span arch bridges.

关键词： steel webs     concrete     box arch     trial design     structural behaviors     finite element method    

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Punching of reinforced concrete slab without shear reinforcement: Standard models and new proposal

Luisa PANI, Flavio STOCHINO

《结构与土木工程前沿（英文）》 2020年 第14卷 第5期   页码 1196-1214 doi: 10.1007/s11709-020-0662-z

摘要： Reinforced concrete (RC) slabs are characterized by reduced construction time, versatility, and easier space partitioning. Their structural behavior is not straightforward and, specifically, punching shear strength is a current research topic. In this study an experimental database of 113 RC slabs without shear reinforcement under punching loads was compiled using data available in the literature. A sensitivity analysis of the parameters involved in the punching shear strength assessment was conducted, which highlighted the importance of the flexural reinforcement that are not typically considered for punching shear strength. After a discussion of the current international standards, a new proposed model for punching shear strength and rotation of RC slabs without shear reinforcement was discussed. It was based on a simplified load-rotation curve and new failure criteria that takes into account the flexural reinforcement effects. This experimental database was used to validate the approaches of the current international standards as well as the new proposed model. The latter proved to be a potentially useful design tool.

关键词： punching shear strength     reinforced concrete     slabs     reinforcement ratio    

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Performance of fixed beam without interacting bars

Aydin SHISHEGARAN, Behnam KARAMI, Timon RABCZUK, Arshia SHISHEGARAN, Mohammad Ali NAGHSH, Mohammreza MOHAMMAD KHANI

《结构与土木工程前沿（英文）》 2020年 第14卷 第5期   页码 1180-1195 doi: 10.1007/s11709-020-0661-0

摘要： Increasing the bending capacity of reinforced concrete (RC) elements is one of important topics in structure engineering. The goal of this study is to develop a transferred stress system (TSS) on longitudinal reinforcement bars for increasing the bending capacity of RC frames. The study is divided into two parts, i.e., experimental tests and nonlinear FE analysis. The experiments were carried out to determine the load-deflection curves and crack patterns of the ordinary and TSS fixed frame. The FE models were developed for simulating the fixed frames. The obtained load-deflection results and the observed cracks from the FE analysis and experimental tests are compared to evaluate the validation of the FE nonlinear models. Based on the validated FE models, the stress distribution on the ordinary and TSS bars were evaluated. We found the load carrying capacity and ductility of TSS fixed beam are 29.39% and 23.69% higher compared to those of the ordinary fixed beams. The crack expansion occurs on the ordinary fixed beam, although there are several crack openings at mid-span of the TSS fixed beam. The crack distribution was changed in the TSS fixed frame. The TSS fixed beam is proposed to employ in RC frame instead of ordinary RC beam for improving the performance of RC frame.

关键词： transferred stress system     bending capacity     crack opening     crack propagation     FE nonlinear model     stress distribution    

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Development and clinical trial of a novel bioactive bone cement

LEONG John, LI Zhaoyang, LU William

《医学前沿（英文）》 2008年 第2卷 第2期   页码 117-126 doi: 10.1007/s11684-008-0022-1

摘要： Strontium (Sr) and related compounds have become more attractive in the prevention and treatment of osteoporosis. Previously, we developed a novel bioactive bone cement which is mainly composed of strontium-containing hydroxyapatite (Sr-HA) filler and bisphenol A diglycidylether dimethacrylate (Bis-GMA) resin. This bone cement is superior to conventional polymethylmethacrylate (PMMA) bone cement in bioactivity, biocompatibility, and osseointegration. It also has shown sufficient mechanical strength properties for its use in percutaneous vertebroplasty (PVP) and total hip replacement (THR). In this paper, we review the and clinical evidence for the effectiveness of this bioactive bone cement.

关键词： bioactivity     effectiveness     strontium-containing hydroxyapatite     osseointegration     sufficient mechanical    

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重力储能有望扩大规模

Sean O'Neill

《工程（英文）》 2022年 第14卷 第7期   页码 3-6 doi: 10.1016/j.eng.2022.05.007

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Punching shear behavior of recycled aggregate concrete slabs with and without steel fibres

Jianzhuang XIAO, Wan WANG, Zhengjiu ZHOU, Mathews M. TAWANA

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 725-740 doi: 10.1007/s11709-018-0510-6

摘要： A study on the punching shear behavior of 8 slabs with recycled aggregate concrete (RAC) was carried out. The two main factors considered were the recycled coarse aggregate (RCA) replacement percentage and the steel fibre volumetric ratio. The failure pattern, load-displacement curves, energy consumption and the punching shear capacity of the slabs were intensively investigated. It was concluded that the punching shear capacity, ductility and energy consumption decreased with the increase of RCA replacement percentage. Research findings indicated that the incorporation of steel fibres could not only improve the energy dissipation capacity and the punching shear capacity of the slab, but also effectively improve the integrity of the slab tension surface and thereby changing the trend from typical punching failure pattern to bending-punching failure pattern. On the basis of the test, the punching shear capacity formula of RAC slabs with and without steel fibres was proposed and discussed.

关键词： recycled aggregate concrete     steel fibres     slab     punching shear     recycled coarse aggregates replacement percentage    

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Expression and function of DMT1 without IRE in C6 cells mediated by recombinant adenovirus

Xixun DU*, Huamin XU*, Hong JIANG, Jun WANG, Lei WANG, Junxia XIE

《医学前沿（英文）》 2009年 第3卷 第1期   页码 67-71 doi: 10.1007/s11684-009-0010-0

摘要： Divalent metal transporter 1 (DMT1) is a ferrous iron import protein. The improper expression of DMT1 is involved in neurodegenerative diseases. In the present study, we constructed a recombinant adenovirus containing the gene of DMT1 without the iron response element (DMT1-IRE) and investigated its expression and function in the C6 glioma cell line. The DMT1-IRE gene, obtained by RT-PCR, was cloned into the shuttle plasmid pAdTrack-CMV containing green fluorescent protein (GFP) reporter gene. Linearized plasmid pAdTrack-CMV-DMT1-IRE was subsequently co-transformed into ( ) BJ5183 cells along with an adenoviral backbone plasmid pAdEasy-1 after digestion with I. I-digested pAdEasy1-DMT1-IRE was then transfected into E1-transformed human embryonic kidney cells (HEK293 cells) , in which recombinant adenoviruses were generated within 7 to 10 days. The results demonstrated that we obtained the DMT1-IRE gene. pAdEasy1-DMT1-IRE yielded a large fragment, plus a smaller fragment of 4.5 kb after digestion with I. PCR confirmed pAdEasy1-DMT1-IRE contained gene DMT1-IRE, indicating the successful construction of recombinant adenovirus plasmid containing DMT1-IRE. GFP fluorescence further confirmed the generation of adenovirus. AdDMT1-IRE could efficiently infect C6 glioma cells. And cell viability decreased in Ad-DMT1-IRE infected cells after iron overload compared to the control. These results suggest that the over expressed DMT1-IRE can aggravate the iron induced cell death due to its iron influx function.

关键词： divalent metal transporter 1     recombinant adenovirus     homologous recombination     iron    

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inhibitor is associated with the reduced risk of all-cause mortality in COVID-19 among patients with/without

《医学前沿（英文）》 2022年 第16卷 第1期   页码 102-110 doi: 10.1007/s11684-021-0850-9

摘要： Consecutively hospitalized patients with confirmed coronavirus disease 2019 (COVID-19) in Wuhan, China were retrospectively enrolled from January 2020 to March 2020 to investigate the association between the use of renin–angiotensin system inhibitor (RAS-I) and the outcome of this disease. Associations between the use of RAS-I (angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB)), ACEI, and ARB and in-hospital mortality were analyzed using multivariate Cox proportional hazards regression models in overall and subgroup of hypertension status. A total of 2771 patients with COVID-19 were included, with moderate and severe cases accounting for 45.0% and 36.5%, respectively. A total of 195 (7.0%) patients died. RAS-I (hazard ratio (HR)=0.499, 95% confidence interval (CI) 0.325–0.767) and ARB (HR=0.410, 95% CI 0.240–0.700) use was associated with a reduced risk of all-cause mortality among patients with COVID-19. For patients with hypertension, RAS-I and ARB applications were also associated with a reduced risk of mortality with HR of 0.352 (95% CI 0.162–0.764) and 0.279 (95% CI 0.115–0.677), respectively. RAS-I exhibited protective effects on the survival outcome of COVID-19. ARB use was associated with a reduced risk of all-cause mortality among patients with COVID-19.

关键词： COVID-19     RAS inhibitor     hypertension     all-cause mortality    

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Small cell carcinoma of the urinary bladder without gross hematuria: a case report

null

《医学前沿（英文）》 2015年 第9卷 第3期   页码 384-387 doi: 10.1007/s11684-015-0405-z

摘要：

Small cell carcinoma of the urinary bladder (SCCB) is a rare and aggressive form of bladder cancer with poor prognosis. Hematuria is the main symptom of this malignancy, and most patients have a history of smoking. The disease incidence of malignant bladder tumors in China is approximately 0.74%. Early and accurate diagnosis of SCCB can ensure timely and appropriate treatment of this malignant disease. Oncologic surgery is the standard treatment; however, it may not be a curative approach. Chemotherapy and/or radiotherapy should be performed following surgical removal. This case report describes a patient with a single neoplasm diagnosed as SCCB that arose because of recurrence of bladder cancer after bladder tumor resection. In contrast to previously reported cases, this patient had no gross hematuria and no history of smoking.

关键词： carcinoma     small cell     urinary bladder neoplasms     diagnosis    

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Cobalt nitride enabled benzimidazoles production from furyl/aryl bio-alcohols and -nitroanilines without

《化学科学与工程前沿（英文）》 2023年 第17卷 第1期   页码 68-81 doi: 10.1007/s11705-022-2174-y

摘要： Benzimidazole derivatives have wide-spectrum biological activities and pharmacological effects, but remain challenging to be produced from biomass feedstocks. Here, we report a green hydrogen transfer strategy for the efficient one-pot production of benzimidazoles from a wide range of bio-alcohols and o-nitroanilines enabled by cobalt nitride species on hierarchically porous and recyclable nitrogen-doped carbon catalysts (Co/CNx-T, T denotes the pyrolysis temperature) without using an external hydrogen source and base additive. Among the tested catalysts, Co/CNx-700 exhibited superior catalytic performance, furnishing 2-substituted benzimidazoles in 65%–92% yields. Detailed mechanistic studies manifest that the coordination between Co2+ and N with appropriate electronic state on the porous nitrogen-doped carbon having structural defects, as well as the remarkable synergetic effect of Co/N dual sites contribute to the pronounced activity of Co/CNx-700, while too high pyrolysis temperature may cause the breakage of the catalyst Co–N bond to lower down its activity. Also, it is revealed that the initial dehydrogenation of bio-alcohol and the subsequent cyclodehydrogenation are closely correlated with the hydrogenation of nitro groups. The catalytic hydrogen transfer-coupling protocol opens a new avenue for the synthesis of N-heterocyclic compounds from biomass.

关键词： biomass conversion     furanic compounds     benzimidazoles     hydrogen transfer     bifunctional catalysis    

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Influencing mechanism of high solid concentration on anaerobic mono-digestion of sewage sludge without

Yuyao ZHANG,Huan LI,Can LIU,Yingchao CHENG

《环境科学与工程前沿（英文）》 2015年 第9卷 第6期   页码 1108-1116 doi: 10.1007/s11783-015-0806-x

摘要： High-solids anaerobic digestion of sewage sludge was a promising process, but high solid concentration negatively influenced methane production. The influencing mechanism was systematically analyzed in this study through a series of static anaerobic digestion experiments at total solids (TS) contents of 3%–15%. The results showed that TS 6% was the boundary between low-solids and high-solids anaerobic digestion, and the accumulative methane yield decreased exponentially when TS increased from 6% to 15%. The performance of anaerobic digestion was directly determined by the efficiency of mass transfer, and the relation between methane yield and sludge diffusive coefficients was well described by a power function. Thus, the increasing TS resulted in an exponential increase in sludge viscosity but an exponential decrease in diffusive coefficient. The blocked mass transfer led to the accumulation of volatile fatty acids (VFAs) and free ammonia. Acetic metabolism was the main process, whereas butyric and propionic metabolisms occurred at the initial stage of high-solids anaerobic digestion. The concentration of VFAs reached the maximum at the initial stage, which were still lower than the threshold influencing methanogens. The concentration of free ammonia increased gradually, and the methanogenesis was inhibited when free ammonia nitrogen exceeded 50 mg·L . Consequently, the deterioration of high-solids anaerobic digestion was related to the blocked mass transfer and the resulting ammonia accumulation.

关键词： anaerobic digestion     methane     sewage sludge     volatile fatty acids     free ammonia    

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标题 作者 时间 类型 操作

Balancing method without trial weights for rotor systems based on similitude scale model

Ruiduo YE, Liping WANG, Xiaojie HOU, Zhong LUO, Qingkai HAN

期刊论文

Negative weights in network time model

Zoltán A. VATTAI, Levente MÁLYUSZ

期刊论文

Development of oxide dispersion strengthened ferritic steels with and without aluminum

Jae Hoon LEE

期刊论文

Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

期刊论文

Trial design of arch bridge of composite box section with steel web-concrete flange

Jiangang WEI, Qingwei HUANG, Baochun CHEN,

期刊论文

Punching of reinforced concrete slab without shear reinforcement: Standard models and new proposal

Luisa PANI, Flavio STOCHINO

期刊论文

Performance of fixed beam without interacting bars

Aydin SHISHEGARAN, Behnam KARAMI, Timon RABCZUK, Arshia SHISHEGARAN, Mohammad Ali NAGHSH, Mohammreza MOHAMMAD KHANI

期刊论文

Development and clinical trial of a novel bioactive bone cement

LEONG John, LI Zhaoyang, LU William

期刊论文

重力储能有望扩大规模

Sean O'Neill

期刊论文

Punching shear behavior of recycled aggregate concrete slabs with and without steel fibres

Jianzhuang XIAO, Wan WANG, Zhengjiu ZHOU, Mathews M. TAWANA

期刊论文

Expression and function of DMT1 without IRE in C6 cells mediated by recombinant adenovirus

Xixun DU*, Huamin XU*, Hong JIANG, Jun WANG, Lei WANG, Junxia XIE

期刊论文

inhibitor is associated with the reduced risk of all-cause mortality in COVID-19 among patients with/without

期刊论文

Small cell carcinoma of the urinary bladder without gross hematuria: a case report

null

期刊论文

Cobalt nitride enabled benzimidazoles production from furyl/aryl bio-alcohols and -nitroanilines without

期刊论文

Influencing mechanism of high solid concentration on anaerobic mono-digestion of sewage sludge without

Yuyao ZHANG,Huan LI,Can LIU,Yingchao CHENG

期刊论文