检索结果-南通市图书馆

Evaluation of particle packing models by comparing with published test results

在线全文

学校读者我要写书评

暂无评论

Particuology 2014年第5期12卷 108-115页

作者： k.w.Chan A.k.H.kwan Department of Civil Engineering The University of Hong Kong

The existing particle packing density models each with two or more parameters accounting for certain particle interactions （the loosening effect parameter, wall effect parameter, wedging effect parameter, and compaction index, denoted by a, b, c, and k, respectively） may be classified into the 2-parameter model （with a and b incorporated）, the compressible model （with a, b, and 1（incorporated）, and the 3- parameter model （with a, b, and c incorporated）. This paper evaluates these models by comparing their respective packing density predictions with the test results published in the literature. It was found that their accuracy varies with both the size ratio and volumetric fractions of the binary mix. In general, when the size ratio is larger than 0.65, all the packing models are sufficiently accurate. However, when the size ratio is smaller than 0.65, some of them become inaccurate and the errors tend to be larger at around the volumetric fractions giving maximum packing density. Relatively, the 3-parameter model is the most accurate and widely applicable.

关键词： Packing density Particle packing models Particle interactions

A review on MBE-grown HgCdSe infrared materials on GaSb(211)B substrates

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第1期28卷 116-125页

作者： Z k Zhang w w Pan J L Liu w Lei Department of Electrical Electronic and Computer EngineeringThe University of Western Australia35 Stirling HighwayCrawley 6009Australia

we review our recent efforts on developing HgCdSe infrared materials on Ga Sb substrates via molecular beam epitaxy(MBE) for fabricating next generation infrared detectors with features of lower production cost and larger focal plane array format size. In order to achieve high-quality HgCdSe epilayers, ZnTe buffer layers are grown before growing HgCdSe, and the study of misfit strain in ZnTe buffer layers shows that the thickness of ZnTe buffer layer needs to be below 300 nm in order to minimize the generation of misfit dislocations. The cut-off wavelength/alloy composition of HgCdSe materials can be varied in a wide range by varying the ratio of Se/Cd beam equivalent pressure during the HgCdSe *** temperature presents significant impact on the material quality of HgCdSe, and lower growth temperature leads to higher material quality for HgCdSe. Typically, long-wave infrared HgCdSe(x = 0.18, cut-off wavelength of 10.4 μm at 80 k) presents an electron mobility as high as 1.3×10~5cm^2·V^(-1)·s^(-1), a background electron concentration as low as 1.6×10^(16)cm^(-3), and a minority carrier lifetime as long as 2.2 μs. These values of electron mobility and minority carrier lifetime represent a significant improvement on previous studies of MBE-grown HgCdSe reported in the open literatures,and are comparable to those of counterpart HgCdTe materials grown on lattice-matched CdZnTe substrates. These results indicate that HgCdSe grown at the University of western Australia, especially long-wave infrared can meet the basic material quality requirements for making high performance infrared detectors although further effort is required to control the background electron concentration to below 10^(15)cm^(-3). More importantly, even higher quality HgCdSe materials on GaSb are expected by further optimizing the growth conditions, using higher purity Se source material, and implementing postgrowth thermal annealing and defect/impurity gettering/filtering. Our results demonst

关键词： infrared detector HgCdSe GaSb molecular beam epitaxy

Topological phase transitions and Majorana zero modes induced by the periodic potential in an antiferromagnetic chain

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第8期75卷 156-162页

作者： k w Shen Q Chen College of Physics and Mechanical&Electrical Engineering Jishou UniversityJishou 416000China School of Computational Science and Electronics Hunan Institute of EngineeringXiangtan 411104China

we investigate the topological properties of an antiferromagnetic(AFM)chain with an on-site periodic potential,considering the intrinsic spin–orbit coupling and an external Zeeman field along with the *** results indicate that Majorana zero modes(MZMs)can be observed by adjusting the strength of the periodic *** have calculated the energy spectrum,the wave-function and transport properties,and all these results support the existence of MZMs in the AFM ***,multiple topological phase transitions occur as the strength of the periodic potential changes,and several regions support MZMs.

关键词： AFM chain Majorana zero modes topological phase transitions periodic potential

Sensorless control for hysteresis compensation of AFM scanner by modified Rayleigh model

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2010年第6期17卷 1243-1246页

作者： PARk J k MOON w k Department of Mechanical Engineering Changwon National UniversityChangwon 641-773Korea Department of Mechanical Engineering Pohang Unive rsity of Science and TechnologyPohang 790-784Korea

A novel modified Rayleigh model was developed for compensating hysteresis problem of an atomic force microscope(AFM) *** high driving fields,piezoelectric actuators that integrated a scanner have severe hysteresis,which can cause serious displacement *** hysteresis is from various origins including movement of defects,grain boundary effects,and displacement of ***,because its characteristic is stochastic,it is almost impossible to predict the piezoelectric hysteresis ***,it was predicted phenomenologically,which means that the relationship between inputs and outputs is *** typical phenomenological approach is the Rayleigh ***,the model has the discrepancy with experiment result as the fields *** overcome the demerit of the Rayleigh model,a modified Rayleigh model was *** the modified Rayleigh model,each coefficient should be defined differently according to the field direction due to the increase of the asymmetry in the high *** applying an inverse form of this modified Rayleigh model to an AFM scanner,it is proved that hysteresis can be compensated to a position error of less than 5%.This model has the merits of reducing complicated fitting procedures and saving computation time compared with the Preisach model.

关键词： piezoelectric stack actuator hysteresis compensation Rayleigh model atomic force microscopy

Effect of monovalent charge compensators on the photoluminescence properties of Ca_(3)(PO_(4))_(2):Tb^(3+),A^(+)(A=Li,Na,k)phosphors

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第23期82卷 187-196页

作者： G.w.Jung k.Park Faculty of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul05006Republic of Korea

Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,k),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state *** the prepared phosphors formed a rhombohedral unit cell with the R3c space *** improve the photoluminescence(PL)properties of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor,monovalent charge compensators such as Li^(+),NA^(+),and k^(+)were added to the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)*** charge compensators acted as fluxes,so they improved the *** excitation and emission properties were significantly improved through the incorporation of charge *** particular,among the charge compensators,Li^(+)ion substantially enhanced the emission intensity and color ***,considering the evaporation of Li_(2)CO_(3)during the annealing process,we optimized the concentration of Li^(+)charge compensator to enhance its PL ***,the green emission intensity of the Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.385 Li^(+)phosphor was 260%higher than that of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)*** believe that the effect of charge compensators on the PL properties and the optimum concentration of Li^(+)cha rge compensator are useful for the design of phosphors in light-emitting diodes.

关键词： Optical properties Ca_(3)(PO_(4))_(2) Emission Excitation Charge compensator

Supporting farmer-managed irrigation systems in the Shigar valley, karakorum： Role of the government and Aga khan Rural Support Programme

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2017年第10期14卷 2064-2081页

作者： Joseph k.w.HILL Department of Rural Management Xavier Institute of Social Sciences (XISS) Dr Gamil Bulcke Path Post Box 7 Ranchi- 834001 India

Farmer-managed irrigation systems(FMIS) in the high altitude valleys of the karakorum,Pakistan, continue to be managed effectively despite increased pressure on the social arrangements that sustain them. Colonial era records shows that over a century ago government agencies undertook irrigation support projects. In the past three decades,government agencies and the non-government agency Aga khan Rural Support Programme(AkRSP), which channels foreign funds into the region, have actively engaged in the provision of irrigation support. This article seeks to explore whether such projects support or undermine farmer-managed irrigation systems and the complex institutional arrangements that underpin them. Field research using ethnographic and participatory methods was conducted in spring 2013 in the upper Shigar valley, Skardu district, GilgitBaltistan. The findings show that irrigation development is a political activity that involves village-based actors, religious leaders, local politicians,and government and non-government *** agencies operate in a largely top-down,engineering mode, their larger projects limited to villages suffering water scarcity. The local government provides small funds for renovation work of FMIS,though allocation of funds is highly politicized. Nongovernment agencies, for a variety of reasons including donor-funding cycles, apply a one-size-fitsall ‘participatory' model in an attempt to socially engineer rules and institutions. In communities divided by factionalism the use of such external models that stress formation of committees are unlikely to yield positive results, and could instead contribute to undermining the very systems they seek to support. This research argues that irrigation interventions should take care to build upon the rich and complex social arrangements that have sustained FMIS through the centuries.

关键词： Farmer-managed irrigation systems Institutional arrangements Government Aga khan Rural Support Programme Shigar valley karakorum

AR-assisted robot welding programming

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2020年第1期8卷 40-48页

作者： S.k.Ong A.Y.C.Nee A.w.w.Yew N.k.Thanigaivel Department of Mechanical Engineering Faculty of EngineeringNational University of SingaporeSingapore

Robotic welding demands high accuracy and ***,robot programming is often a tedious and time-consuming process that requires expert *** paper presents an augmented reality assisted robot welding task programming(ARwP)system using a user-friendly augmented reality(AR)interface that simplifies and speeds up the programming of robotic welding *** ARwP system makes the programming of robot welding tasks more user-friendly and reduces the need for trained programmers and expertise in specific robotic *** AR interface simplifies the definition of a welding path as well as the welding gun orientation,and the system;the system can locate the welding seam of a workpiece quickly and generate a viable welding path based on the user *** developed system is integrated with the touch-sensing capability of welding robots in order to locate the welding path accurately based on the user input,for fillet *** system is applicable to other welding processes and methods of seam *** system implementation is described and evaluated with a case study.

关键词： Augmented reality(AR) Robot programming welding Seam tracking

NECAB family of neuronal calcium-binding proteins in health and disease

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

Neural Regeneration Research 2025年第5期20卷 1236-1243页

作者： Diones Bueno Michael k.E.Schafer Sudena wang Michael J.Schmeisser Axel Methner Institute for Molecular Medicine University Medical Center of the Johannes Gutenberg-UniversityMainzGermany Department of Anesthesiology University Medical Center of the Johannes Gutenberg-UniversityMainzGermany Institute of Anatomy University Medical Center of the Johannes Gutenberg-UniversityMainzGermany

The N-terminal EF-hand calcium-binding proteins 1–3(NECAB1–3) constitute a family of predominantly neuronal proteins characterized by the presence of at least one EF-hand calcium-binding domain and a functionally less well characterized C-terminal antibiotic biosynthesis monooxygenase domain. All three family members were initially discovered due to their interactions with other proteins. NECAB1 associates with synaptotagmin-1, a critical neuronal protein involved in membrane trafficking and synaptic vesicle exocytosis. NECAB2 interacts with predominantly striatal G-protein-coupled receptors, while NECAB3 partners with amyloid-β A4 precursor protein-binding family A members 2 and 3, key regulators of amyloid-β production. This demonstrates the capacity of the family for interactions with various classes of proteins. NECAB proteins exhibit distinct subcellular localizations: NECAB1 is found in the nucleus and cytosol, NECAB2 resides in endosomes and the plasma membrane, and NECAB3 is present in the endoplasmic reticulum and Golgi apparatus. The antibiotic biosynthesis monooxygenase domain, an evolutionarily ancient component, is akin to atypical heme oxygenases in prokaryotes but is not wellcharacterized in vertebrates. Prokaryotic antibiotic biosynthesis monooxygenase domains typically form dimers, suggesting that calcium-mediated conformational changes in NECAB proteins may induce antibiotic biosynthesis monooxygenase domain dimerization, potentially activating some enzymatic properties. However, the substrate for this enzymatic activity remains uncertain. Alternatively, calcium-mediated conformational changes might influence protein interactions or the subcellular localization of NECAB proteins by controlling the availability of protein–protein interaction domains situated between the EF hands and the antibiotic biosynthesis monooxygenase domain. This review summarizes what is known about genomic organization, tissue expression, intracellular localization, interac

关键词： calcium EF hand mitochondria nervous system signal transduction

Fabrication of curved micro structures on photoresist layer

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 100-103页

作者： Jae Sung YOON Tae-Jin JE Doo-Sun CHOI Sung Hwan CHANG kyung-Hyun whang Nano Mechanical Systems Research Division Korea Institute of Machinery and Materials (KIMM) Daejeon 305-343 Korea

A novel fabrication process for micro patterns with curvature was introduced. The curved structures were made by compensating rectangular micro structures with liquid photoresist layer. Because of the surface tension of the liquid in micro scale, various shapes of meniscus can he made on the micro channels. The micro channels were made on the silicon suhstrate in advance, and then the liquid layer was coated on the micro channels. From the nature of liquid behavior, the curved patterns with smooth surface are obtained, which cannot be made easily with the conventional mechanical machining, as well as with the microfabrication processes, such as wet and dry etching. with this principle, it is expected that the smooth and curved surfaces can be made by simple processes and the results can be applied widely, such as optical patterns.

关键词： micro pattern liquid layer MEMS micro channel silicon substrate