检索结果-南通市图书馆

MMPP/M/C queue with congestion-based staffing policy and applications in operations of steel industry

Journal of Iron and Steel Research International 2019年第7期26卷 659-668页

作者： Yan-he Jia Li-xin tang Zhe George Zhang Xiao-feng Chen Liaoning Key Laboratory of Manufacturing System and Logistics Institute of Industrial and Systems Engineering Northeastern University Shenyang 110819 Liaoning China Beedie School of Business Simon Fraser University Burnaby BC V5A 1S6 Canada Department of Decision Sciences Western Washington University Bellingham WA 98225 USA

A queueing model of the Markov-modulated Poisson process (MMPP) with thresholds was investigated. The customer arrival with various arrival rates in the model was viewed as the MMPP. In contrast to the Poisson, s arrival process, the MMPP can better describe the situation that the arrival rate changes with changing conditions;therefore, the model fits better with reality. The threshold conversion was added to the model based on the general MMPP/M/C model. When the number of customers in the system exceeds a threshold, all servers work to serve;when the number of customers in the system is less than another threshold, some servers are shut down. This is the congestion-based staffing policy with two thresholds. Specifically, the problems in the slab stocking stage of slab production at the Iron and Steel Complex in China were analysed. In the slab production process, because the rate of the upstream steelmaking is not constant, the rate of slab reaching the slab yard is uncertain. The crane service is used to store slabs in a warehouse. Because the slab arrival rate varies, different numbers of cranes in service need to be optimized for cost control. Thus, MMPP was used to describe slab arrival with varied arrival rates. Therefore, an MMPP/M/C queue with thresholds was used to analyse and solve the practical problems, and the optimal number of service cranes was obtained to minimize the cost of slab stocking.

关键词： Markov-modulated Poisson process Matrix geometry Congestion-based staffing policy Threshold conversion Slab Crane

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Roles of paroxetine and corticosterone on adult mammalian ciliary body cell proliferation

引用

Chinese Medical Journal 2010年第10期123卷 1305-1310页

作者： waNG Hua LAU Benson WM YAU Suk-yu LI Suk-yee LEUNG Nelson waNG Ning-li tang Siu-wa LEE Tatia MC SO Kwok-fai Department of Anatomy Li Ka Shing Faculty of Medicine the University of Hong Kong Hong Kong Special Administrative Region China the State Key Laboratory of Brain and Cognitive Sciences the University of Hong Kong Hong Kong Special Administrative Region China Neuropsychology Laboratory the University of Hong Kong Hong Kong Special Administrative Region China Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing Ophthalmology & Visual Sciences Key Laboratory Beijing 100730 China Joint Laboratory for Brain Function and Health (BFAH) Jinan University and the University of Hong Kong

Background The neurogenesis in retina of adult mammals is generally abolished, and this renders the retina lack of regenerative capacity. Despite this, there is a small population of nestin-positive cells in the ciliary epithelium which retains neurogenic potential. The present study aimed at investigating the effect of two drugs, corticosterone and paroxetine, on the cell proliferation of the ciliary body. Methods Adult Sprague-Dawley rats were given vehicle, corticosterone, paroxetine, or both corticosterone and paroxetine treatment for 14 days. Cell proliferation in the ciliary body was quantified using 5-bromo-2-deoxyuridine （BrdU） immunohistochemistry. Co-labelling of BrdU and stem cell marker was used to phenotype the BrdU immunoreactive cells. Results Corticosterone treatment suppressed while paroxetine treatment increased the cell proliferation of the ciliary body. Co-labelling with cell markers revealed that the BrdU positive cells also showed nestin expression but not glial fJbrillary acidic protein （GFAP）. Conclusions The results illustrate that proliferation of retinal progenitor cells situated in ciliary body are subjected to regulation by selective serotonin reuptake Jnhibitors （SSRI） and corticosteroJd, which is similar to our previous findings in neurogenic regions in central nervous system （CNS）. Paroxetine treatment could reverse the suppressive effect of corticosterone on ciliary body cell proliferation. This provides information for future investigation of retinal stem cell biology and potential treatment of retinal degenerative diseases.

关键词： paroxetine 5-bromo-2-deoxyuridine corticosterone ciliary body cell proliferation neurogenesis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Design strategy of phase and microstructure of Si_(3)N_(4) ceramics with simultaneously high hardness and toughness

引用

Journal of Advanced Ceramics 2023年第1期12卷 122-131页

作者： Shao-Jun tang Wei-Ming GUO Shi-Kuan SUN Hua-Tay LIN School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China School of Material Science and Energy Engineering Foshan UniversityFoshan 528000China

Aiming to achieve silicon nitride( Si_(3)N_(4))ceramics with high hardness and high toughness,the relationships among phase composition,microstructure,and mechanical properties of Si_(3)N_(4) ceramics prepared by spark plasma sintering(SPS)at temperatures ranging from 1500 to 1800℃were investigated in this *** stages with different phase and microstructure features were observed and ***α-βphase transformation occurs first,and the development and growth of grains lag *** the first stage,the average grain size remains basically unchanged,and the hardness maintains at a value of~20.18±0.26 GPa,despite theβ- Si_(3)N_(4) phase fraction increases from 7.67 to 57.34 wt%.Subsequently,the equiaxed grains transform into rod-like grains with a high aspect ratio via the reprecipitation process,resulting in a significant increase in the fracture toughness from 3.36±0.62 to 7.11±0.15 MPa·m^(1/2).In the second stage of sintering process,the fraction ofβ- Si_(3)N_(4) phase increases to 100.00 wt%,and the grain growth also rapidly ***,the fracture toughness increases slightly to 7.61±0.42 MPa·m^(1/2),but the hardness reduces to 16.80±0.20 *** current results demonstrate that the phase contents ofβ- Si_(3)N_(4) and the microstructure shall be carefully tailored to achieve high-performance Si_(3)N_(4) ceramics. Si_(3)N_(4) ceramics with a finegrained bimodal microstructure,consisting of the mainα-andβ-phases,can exhibit the optimized combination of hardness and toughness.

关键词： silicon nitride(Si_(3)N_(4)) phase composition microstructure hardness toughness

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Structural, densitometric and biomechanical evaluations of Chinese patients with long-term bisphosphonate treatment

引用

Chinese Medical Journal 2013年第1期126卷 27-33页

作者： LEUNG Kwok-sui tang Ning James Griffith CHOY Tak-Kee HUNG Vivian Wing-Yin MOK Hoi-wa SHI Lin LEUNG Ping-Chung CHEUNG Wing-Hoi Department of Orthopaedics and Traumatology and Bone Quality and Health Center The Chinese University of Hong Kong Shatin Hong Kong SAR China Department of Imaging and Interventional Radiology The Chinese University of Hong Kong Shatin Hong Kong SAR China The Jockey Club Center for Osteoporosis Care and Control The Chinese University of Hong Kong Shatin Hong Kong SAR China Orthopaedic Research Laboratory of Translational MedicineResearch and Development Center Institute of Biomedical andHealth Engineering Shenzhen Institutes of Advanced TechnologyChinese Academy of Sciences China

Background The association of long-term bisphosphonate treatment for osteoporosis and related safety problems such as atypical fractures were not clearly defined. This study was to evaluate the structural, densitometric and biomechanical properties of the prolonged bisphosphonate-loaded bones. Methods Bone mineral density （BMD） at hip and femoral midshaft, bone cross-sectional area, moment of inertia of both femurs, bone formation and resorption biochemical markers were compared between 28 elderly with at least 4 years of bisphosphonate treatment from 2002 through 2006 and age-matched group of 37 elderly. Results The total hip BMD and t-score were found not different between two groups. However, bisphosphonate treated patients were found to have significantly lower bone mineral content in the femoral shaft （P 〈0.05）; morphological study showed lower cross-sectional area in subtrochanteric and mid-diaphyseal region and thus significantly lower moment of inertia （P 〈0.01）. High resolution-peripheral quantitative computed tomography showed significantly decreased trabeculardensity, bone volume ratio, trabecular number but increased trabecular spacing in tibia and distal radius. Finite element analysis further confirmed significantly lower stiffness and failure load in tibia. Biochemical studies also showed lower bone resorption and severely suppressed bone formation activity （P 〈0.001）. Conclusions The unchanged total hip BMD between two groups confirmed the beneficial effects of bisphosphonate on trabecular bone, thus preventing osteoporotic fractures at large in previous studies. However, the inferior structural, densitometric and biomechanical properties at cortical bones, especially femur midshaft, need a special attention to look into the association between long-term bisphosphonate intake and the occurrence of stress fractures. When patients taking bisphosphonate complain of proximal thigh pain or discomfort, plain X-ray film can be the first line screening. All

关键词： bisphosphonate bone mineral density moment of inertia HR-pQCT cortical bone

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Storage stability of vitamin C fortified purple mashed potatoes processed with microwave-assisted thermal sterilization system

引用

Food Innovation and Advances 2023年第2期2卷 106-114页

作者： Juhi Patel Ashutos Parhi Zhongwei tang Juming tang Shyam S.Sablani Department of Biological Systems Engineering Washington State UniversityPO Box-646120WA 99164-6120USA Nutrition Dietetics and Food Sciences Department(NDFS)Utah State University8700 Old Main HillLoganUT 84322-8700USA

Quality changes in ready-to-eat,shelf-stable foods,during storage can be influenced by many factors,such as processing,storage conditions,and the barrier properties of the *** research investigated retention of vitamin C and anthocyanin in purple mashed potatoes as influenced by packaging barrier properties and encapsulation during storage after microwave assisted thermal *** mashed potatoes fortified with encapsulated(EVC)or non-encapsulated vitamin C(NVC)were packaged in two high-barrier polymer pouches(TLMO and PAA),processed with a pilot-scale microwave assisted thermal sterilization(MATS)system(F0=10.7 min),and stored at 37.8°C for 7 *** processing caused a significant increase(Pwater vapor transmission rate(WVTRs)than TLMO films,which resulted in a significantly higher(P<0.05)weight loss in the samples packaged in PAA pouches than TLMO *** mashed potatoes containing encapsulated vitamin C in both TLMO and PAA pouches showed the highest retention over 2 months of storage at 37.8°C than non-encapsulated vitamin ***,purple mashed potatoes exposed to 700 lumens light showed a significantly higher(P<0.05)deterioration in the anthocyanin,total phenolic content,color,and vitamin ***,MATS processed purple mashed potatoes in high barrier polymeric packaging can minimize the quality changes when stored in dark conditions during storage and have an extended shelf life.

关键词： microwave thermal vitamin

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Does Innovation Matter for Chinese High-Tech Exports？ A Firm-Level Analysis

引用

Frontiers of Economics in China-Selected Publications from Chinese Universities 2012年第2期7卷 218-245页

作者： Dahai Fu Yanrui Wu Yihong tang Uwa Business School University of Western AustraliaCrawleyWA6009Australia School of International Trade and Economics Central University of Finance and EconomicsBeijing 100081China

Abstract This paper investigates the impact of innovation on export decisions of Chinese high-tech firms during the period of 2005-2007. Using a parametric, instrumental variable approach and a non-parametric matching method, we find that firm-level innovation efforts, measured by R＆D spending and new product output, play only a minor role for domestic exporters. Foreign-invested firms dominate the high-tech exports but do not rely on indigenous innovation activities. These results demonstrate that the success of Chinese high-tech exports does not result from heavy R＆D expenditure and technological progress. Moreover, different types of innovation measures show different impacts on the likelihood of exporting. The impacts of innovation on exporting vary widely across industries and Chinese regions.

关键词： exports innovation high technology China

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Surface Ozone in Jiuzhaigou National Park, Eastern Rim of the Qinghai-Tibet Plateau, China

引用

Journal of Mountain Science 2012年第5期9卷 687-696页

作者： QIAO Xue tang Ya Daniel JAFFE CHEN Pan XIAO Weiyang DENG Guiping Department of Environment College of Architecture and EnvironmentSichuan UniversityNo 24South Section OneFirst Ring RoadChengdu 61o065China Department of Atmospheric Sciences University of Washington4o8Atmospheric Sciences-Geophysics(ATG)BuildingBox 351640SeattleWA 98195USA Jiuzhaigou Administration Bureau Jiuzhaigou County 623407Sichuan ProvinceChina

Located in southwestern China, Jiuzhaigou National Park is one of the most popular tourism destinations in China, famous for its unique aquatic ecosystems and beautiful forests. However, plants in the park may be at high ozone risk as a result of the intensive use of diesel tour buses in the park. In addition, Jiuzhaigou is close to a region with relatively high regional anthropogenic NOn emissions. During the growing season, also the peak season of tourism, we measured ozone concentration at two sites within the Park and these were： Jiuzhaigou Bureau （JB） and Long Lake （LL）. The results indicate that ozone concentrations were not high enough to cause foliar injury during the monitoring period, although the risk of ozone to plants was higher in spring than in summer and autumn. Diurnal ozone cycles at JB and LL displayed significantly higher ozone concentrations in the daytime than in the nighttime, suggesting photochemical production of ozone during the day and ozone deposition during the night as a result of the nocturnal boundary layer. In parallel with the seasonal change of background surface ozone in the Northern Hemisphere, maximum daily 8-h average ozone concentration （MDA8） and daily ozone concentration decreased from spring to autumn at the two sites. This temporal variation in Jiuzhaigou wasmost likely associated with the downward mixing of ozone-rich air from the free troposphere, because all the high-ozone events （MDA8 〉 70.0 ppb） were observed in spring and ozone-rich air from the free troposphere was the dominant cause. In summary, our data suggest that ozone concentrations in Jiuzhaigou were more affected by the regional-scale of background pattern in air quality and meteorological conditions than by local tourist activities.

关键词： Free troposphere Photochemicalproduction of ozone Surface ozone Mountainousregion Tourism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Detection of methane plumes in the water column of Logatchev hydrothermal vent field,Mid-Atlantic Ridge

引用

Chinese Science Bulletin 2007年第15期52卷 2140-2146页

作者： ZHOU HuaiYang WU ZiJun PENG XiaoTong JIANG Lei tang Song Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Institute of Polar Environment University of Science and Technology of China Hefei 230026 China

During DY105-17 cruise onboard the R/V "Da Yang Yi Hao" in 2005,methane concentrations in the wa-ter column above Logachev hydrothermal vent field were measured by applying stripping/trapping-gas chromatographic (GC) and the distinct methane plumes were detected. Results show that the back-ground methane concentration within the Logachev area is from 1.05 nmol/L to 1.68 nmol/L,signifi-cantly higher than the background level of the Atlantic abyssal plain of 0.4―0.5 nmol/L,suggesting that hydrothermal venting is a major source of dissolved methane to the ocean. The highest anomalies of methane concentrations in the water column range from 7.14 nmol/L to 113.9 nmol/L and occur just at 180―500 m above the seafloor. The distribution of methane concentration and the structural charac-teristics of hydrothermal plumes are strongly influenced by the supply of underlying hydrothermal fluids,the mixing process of ocean bottom currents and the microbial oxidation. Furthermore,the dif-ferences in distribution of methane plume between the station MAR-CTD3 and the other stations indi-cate a probable unknown hydrothermal vent site nearby. There occurs high concentration of methane along with temperature and nephelometry anomalies,which strongly confirms that the subtle meas-urement of methane concentration in water column is one of the effective ways to locate active sites of hydrothermal venting.

关键词：甲烷浓度异常热气流层离法

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

REMAPPING DIGITAL OPERATIONS iClick is promoting big data technologies among companies to facilitate high-quality economic growth

引用

China Report ASEAN 2021年第5期6卷 48-49页

作者： Xin Lida Long wa 不详

As traditional retail was pummeled by the COVID-19 pandemic,retailers were forced to accelerate integration of online and offline *** Jian,CEO of iClick Interactive,a solution provider for digital business operations,has been urging retail companies,service providers,and business platforms to keep pace with the transformation as COVID-19 prevention and control measures become normalized and profound changes take place in business operations and consumer *** quality of the growth of the digital economy is improving rapidly,and business activities including transactions and customer communication with sellers have transformed into data records.

关键词： companies operations prevention

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Studies of poly-L-lysine-starch nanoparticle preparation and its application as gene carrier

引用

Science China Chemistry 2005年第2期48卷 162-166页

作者： XIAO Suyao LIU Xuanming TONG Chunyi LIU Jun tang Dongying ZHAO Lijian Institute of Life Science and Biotechnology College of Chemistry & Chemical Engineering Hunan University Changsha 410082 China Institute of Life Science and Biotechnology College of Chemistry & Chemical Engineering Hunan University Changsha 410082 China Institute of Life Science and Biotechnology College of Chemistry & Chemical Engineering Hunan University Changsha 410082 China Institute of Life Science and Biotechnology College of Chemistry & Chemical Engineering Hunan University Changsha 410082 China Institute of Life Science and Biotechnology College of Chemistry & Chemical Engineering Hunan University Changsha 410082 China Institute of Life Science and Biotechnology College of Chemistry & Chemical Engineering Hunan University Changsha 410082 China

Anion starch nanoparticle (StNP) with a diameter of 50 nm was prepared in wa- ter-in-oil microemulsion, with soluble starch as raw materials and POCl3 as crosslinking agent. PLL-StNP was prepared by linking poly-L-lysine (PLL) on the surface of StNP. At the same time, the size of PLL-StNP and its stability in aqueous solution were checked by AFM. The analysis of plasmid DNA binding, DNase I enzymatic degradation, toxicity and transfection were done. We discovered that PLL-StNP may be used as non-virus nanoparticle gene carrier. And we devel- oped the method of preparing PLL-StNP gene carrier and used it in cell transfection. As non-virus gene carrier, PLL-StNP has some advantages, such as large load of DNA, high transfection effi- ciency, low cell toxicity and biodegradability.

关键词： anion starch nanoparticle, poly-L-lysine, non-virus gene carrier, cell transfection.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：