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排序方式: 共有165条查询结果,搜索用时 15 毫秒
1.
The convective batch drying of Western Hemlock hog fuel-sized particles in fixed beds under various operating conditions quantiatively established the effect of factors which govern the drying process. A correlation was obtained for the Nusselt number during the heat transfer controlled period. Under specific conditions, the existence of a unified characteristic drying rate curve was confirmed. Drying behaviour as described by the receding plane model provided a mathematical expression for such a curve. The existence of an inversion point temperature was experimentally confirmed. 相似文献
2.
In this paper, the problem of motion planning for parallel robots in the presence of static and dynamic obstacles has been investigated. The proposed algorithm can be regarded as a synergy of convex optimization with discrete optimization and receding horizon. This algorithm has several advantages, including absence of trapping in local optimums and a high computational speed. This problem has been fully analyzed for two three-DOF parallel robots, ie 3s-RPR parallel mechanism and the so-called Tripteron, while the shortest path is selected as the objective function. It should be noted that the first case study is a parallel mechanism with complex singularity loci expression from a convex optimization problem standpoint, while the second case is a parallel manipulator for which each limb has two links, an issue which increases the complexity of the optimization problem. Since some of the constraints are non-convex, two approaches are introduced in order to convexify them: (1) A McCormick-based relaxation merged with a branch-and-prune algorithm to prevent it from becoming too loose and (2) a first-order approximation which linearizes the non-convex quadratic constraints. The computational time for the approaches presented in this paper is considerably low, which will pave the way for online applications. 相似文献
3.
Arrays of precisely positioned single crystal silicon nanopillars, nanoneedles, and nanoblades with minimum feature sizes as small as 30 nm are fabricated using entirely scalable top-down fabrication techniques. Using the same scalable technologies, devices consisting of electrically connected silicon nanopillars with multiple addressable electrodes for each nanostructure are realized. The arrays of nanopillars, nanoneedles, and nanoblades are shown to exhibit Raman signal enhancement on 1,2-benzenedithiol monolayers, opening a path to nanodevices that manipulate, position, detect and analyze molecules. 相似文献
4.
Adhesion plays an important role in the final properties of nanocomposites. This study explored the surface interaction of
cellulose nanocrystals (CNCs) and the effect of CNC sources on adhesion between individual CNCs and the Si tip of an AFM cantilever
using a force mapping technique called FMap. The adhesion between CNCs and a Si tip from five different sources has been studied:
cotton, Whatman filter paper, hemp, softwood chemical kraft pulp, and softwood-dissolving pulp (alistaple). Mica was used
as the background substrate to act as an internal standard. This study’s findings suggest that adhesion is not the same for
all CNCs. Transmission electron microscopy and atomic force microscopy were used to determine the size and shape of each CNC.
The experimental quantitative data showed that adhesion between CNCs and the Si tip has a close correlation with the diameter
of the CNCs. X-ray photoelectron spectroscopy confirmed the presence of sulfate groups on the surface of the CNCs and a correlation
between adhesion and surface chemistry of the CNCs was observed. 相似文献
5.
Jalalzadeh-Esfahani Mehrnoosh Sedaghat Tahereh Beheshti Azizollah Azadi Roya 《Journal of Porous Materials》2022,29(4):1149-1164
Journal of Porous Materials - Benzimidazole functionalized mesoporous silica nanoparticles immobilized Pd(0)/Pd(II) has been proposed as an efficient catalyst for the one-pot preparation of biaryls... 相似文献
6.
Fatemeh Asghari Roya Salehi Marziyeh Agazadeh Effat Alizadeh Khosro Adibkia Mohammad Samiei 《国际聚合物材料杂志》2016,65(14):720-728
The authors aimed to design nanofibrous (NF) scaffolds that facilitate odontogenic and osteogenic differentiation of human dental pulp-derived mesenchymal stem cells (DPSCs) in vitro. For this purpose, hydroxyapatite (HA)–loaded poly (L-lactic acid)/poly (?-caprolactone) (PLLA:PCL 2;1) blend NFs were prepared using the electrospinning method. Alizarin red activity and cell viability were evaluated by MTT assay, and SEM revealed the proliferation properties of NF scaffolds. QRT-PCR results demonstrated that HA-loaded PLLA/PCL can lead to osteoblast/odontoblast differentiation in DPSCs through the up-regulation of related genes, thus indicating that electrospun biodegradable PCL/PLA/HA has remarkable prospects as scaffolds for bone and tooth tissue engineering. 相似文献
7.
Ahmadi Ameneh Sedaghat Tahereh Azadi Roya 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(10):4126-4140
Journal of Inorganic and Organometallic Polymers and Materials - 3-Chloropropyltrimethoxysilane (CPTMS) was grafted on the surface of silica coated Fe3O4 core (Fe3O4@MCM-41) and then condensed with... 相似文献
8.
9.
Ian Laboriante Maxwell Fisch Amir Payamipour Fang Liu Carlo Carraro Roya Maboudian 《Tribology Letters》2011,44(1):13-17
The evolution of morphology, electrical properties, and chemical composition has been studied in cyclically contacting polycrystalline
silicon (polysilicon) surfaces coated with perfluoroalkylsilane self-assembled monolayer (SAM). The microinstrument used is
a MEMS cantilever that is repeatedly actuated out-of-plane to impact a landing pad and is then moved in-plane to enable nondestructive
in situ inspection of the impacted area. Analyses show that a device with a monolayer coating exhibits signs of surface degradation
after a much higher number of cycles than its uncoated counterpart. A sharp increase in contact resistance between the cantilever
and landing pad is observed at ~10 billion cycles for a coated device, versus ~25 million cycles for an uncoated device. Likewise,
the onset of grain fracture in the landing pad occurs at ~25 billion cycles for the SAM-coated device, versus ~3 billion cycles
for its uncoated counterpart. The effectiveness of the monolayer coating diminishes after more than 100 billion contact cycles
as the SAM layer is removed, and the polysilicon substrate becomes susceptible to adhesive wear. 相似文献
10.
Cheung E Mutahar R Assefa F Ververs MT Nasiri SM Borrel A Salama P 《Food and nutrition bulletin》2003,24(3):247-255
In March 2002, there were reports of a hemorrhagic fever outbreak in western Afghanistan. It was later confirmed that the hemorrhagic symptoms and increased mortality were actually due to scurvy. Most aid workers did not include scurvy in the initial differential diagnosis because it is uncommon throughout the world and has mainly been reported in refugee populations in recent times. A rapid assessment confirmed the cases clinically, estimated a prevalence rate of 6.3% (a severe public health problem), and determined that the attack rates peaked each year in January and February (the end of the winter). Many Afghans have limited dietary diversity due to isolated locations, lengthy winters, the continuing drought of the last four years, asset depletion, and loss of livelihood. After numerous food and fortification options to prevent future outbreaks had been considered, vitamin C tablet supplementation was selected because of the relatively rapid response time as compared with other prevention methods. A three-month course of vitamin C tablets was distributed to 827 villages in at-risk areas. The tablets were acceptable and compliance was good. No cases of scurvy were reported for the winter of 2002-03. The case study from Afghanistan demonstrates that scurvy can occur in nonrefugee or nondisplaced populations; vitamin C supplementation can be an effective prevention strategy; there is an urgent need to develop field-friendly techniques to diagnose micronutrient-deficiency diseases; food-security tools should be used to assess and predict risks of nutritional deficiencies; and the humanitarian community should address prevention of scurvy in outbreak-prone areas. 相似文献