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排序方式: 共有61条查询结果,搜索用时 756 毫秒
1.
In this paper a different type II robotic assembly line balancing problem (RALB-II) is considered. One of the two main differences with the existing literature is objective function which is a multi-objective one. The aim is to minimize the cycle time, robot setup costs and robot costs. The second difference is on the procedure proposed to solve the problem. In addition, a new mixed-integer linear programming model is developed. Since the problem is NP-hard, three versions of multi-objective evolution strategies (MOES) are employed. Numerical results show that the proposed hybrid MOES is more efficient.  相似文献   
2.
In this study, various Artificial Neural Networks (ANNs) were developed to estimate the production yield of greenhouse basil in Iran. For this purpose, the data collected by random method from 26 greenhouses in the region during four periods of plant cultivation in 2009–2010. The total input energy and energy ratio for basil production were 14,308,998 MJ ha?1 and 0.02, respectively. The developed ANN was a multilayer perceptron (MLP) with seven neurons in the input layer, one, two and three hidden layer(s) of various numbers of neurons and one neuron (basil yield) in the output layer. The input energies were human labor, diesel fuel, chemical fertilizers, farm yard manure, chemicals, electricity and transportation. Results showed, the ANN model having 7-20-20-1 topology can predict the yield value with higher accuracy. So, this two hidden layer topology was selected as the best model for estimating basil production of regional greenhouses with similar conditions. For the optimal model, the values of the models outputs correlated well with actual outputs, with coefficient of determination (R2) of 0.976. For this configuration, RMSE and MAE values were 0.046 and 0.035, respectively. Sensitivity analysis revealed that chemical fertilizers are the most significant parameter in the basil production.  相似文献   
3.
This paper investigates the potential of pulsed power to sterilize hard and soft tissues and its impact on their physico-mechanical properties. It hypothesizes that pulsed plasma can sterilize both vascular and avascular tissues and the transitive layers in between without deleterious effects on their functional characteristics. Cartilage/bone laminate was chosen as a model to demonstrate the concept, treated at low temperature, at atmospheric pressure, in short durations and in buffered environment using a purposed-built pulsed power unit. Input voltage and time of exposure were assigned as controlling parameters in a full factorial design of experiment to determine physical and mechanical alteration pre- and post-treatment. The results demonstrated that, discharges of 11 kV sterilized samples in 45 s, reducing intrinsic elastic modules from 1.4 ± 0.9 to 0.9 ± 0.6 MPa. There was a decrease of 14.1 % in stiffness and 27.8 % in elastic-strain energy for the top quartile. Mechanical impairment was directly proportional to input voltage (P value < 0.05). Bacterial inactivation was proportional to treatment time for input voltages above 32 V (P < 0.001; R Sq  = 0.98). Thermal analysis revealed that helix-coil transition decelerated with exposure time and collagen fibrils were destabilized as denaturation enthalpy reduced by 200 μV. We concluded by presenting a safe operating threshold for pulsed power plasma as a feasible protocol for effective sterilization of connective tissues with varying level of loss in mechanical robustness which we argue to be acceptable in certain medical and tissue engineering application.  相似文献   
4.
We present a free‐energy driven kinetic Monte Carlo model to simulate homogeneous nucleation of metal nanoparticles (NPs) from vapor phase. The model accounts for monomer‐cluster condensations, cluster–cluster collisions, and cluster evaporations simultaneously. Specifically, we investigate the homogeneous nucleation of Al NPs starting with different initial background temperatures. Our results indicate good agreement with earlier phenomenological studies using the Gibbs# free energy formulation from Classical Nucleation Theory (CNT). Furthermore, nucleation rates for various clusters are calculated through direct cluster observations. The steady‐state nucleation rate estimated using two different approaches namely, the Yasuoka‐Matsumoto (YM) and mean first passage time (MFPT) methods indicate excellent agreement with each other. Finally, our simulation results depict the expected increase in the entropy of mixing as clusters approach the nucleation barrier, followed by its subsequent drastic loss after the critical cluster formation resulting from first‐order phase transitions. © 2017 American Institute of Chemical Engineers AIChE J, 63: 18–28, 2018  相似文献   
5.
Single-Instruction Multiple-Data (SIMD) instructions provide an inexpensive way to exploit the Data-Level Parallelism in multimedia applications. However, the performance improvement obtained by employing SIMD instructions is often limited because frequently many overhead instructions are required to bring data in a form amenable to SIMD processing. In this paper, we employ two techniques to overcome this limitation. The first technique, extended subwords, uses four extra bits for every byte in a media register. This allows many SIMD operations to be performed without overflow and avoids packing/unpacking conversion overhead. The second technique, Matrix Register File (MRF), allows flexible row-wise as well as column-wise access to the register file. It is useful for many two-dimensional multimedia algorithms such as the (I) Discrete Cosine Transform, 2 × 2 Haar Transform, and pixel padding. In addition, we propose a few new media instructions. Experimental results obtained by extending the SimpleScalar toolset show that these techniques improve performance by up to a factor of 4.5 compared to a conventional SIMD instruction set extension.  相似文献   
6.
Indium has been used as an alternative channel implant in submicrometer-channel Si MOSFETs in order to obtain highly nonuniform channel doping. Superior device characteristics have been obtained down to 0.17-μm channel length. The device characteristics have been compared to those of uniform boron-implanted short-channel MOSFETs used in a 0.25-μm CMOS technology. Results indicate that NMOSFETs with nonuniform channel doping obtained with indium have superior short-channel effect (SCE) when compared to NMOSFETs with uniformly (boron) doped channel  相似文献   
7.
Lower Cretaceous Shurijeh–Shatlyk Formations host some of the main reservoirs in the Kopeh Dagh-Amu Darya Basin.Exploration in this area so far has focused on the development of structural traps, but recognition of stratigraphic traps in this area is of increasing importance. Integration of 3D seismic data with borehole data from thirteen wells and five outcrop sections was used to identify potential reservoir intervals and survey the hydrocarbon trap types in the East Kopeh Dagh Foldbelt(NE Iran). Analyses of horizontal slices indicated that the lower Shurijeh was deposited in a braided fluvial system.Generally, three types of channel were identified in the lower Shurijeh Formation: type 1, which is low-sinuosity channels interpreted to be filled with non-reservoir fine-grained facies; type 2, which is a moderately sinuous sand-filled channel with good prospectively; and type 3, which is narrow, high sinuosity channel filled with fine-grained sediments. Results indicate that upper Shurijeh–Shatlyk Formations were deposited in fluvial to delta and shallow marine environments. The identified delta forms the second reservoir zone in the Khangiran Field. Study of the stratigraphic aspects of the Shurijeh succession indicates that both lower and upper Shurijeh reservoirs are stratigraphic reservoir traps that improved during folding.  相似文献   
8.
9.
In this work, we fabricated ZnO and ZnO/CuO nanocomposites using Mentha longifolia leaf extract as a natural, non-toxic, and efficient stabilizer. Anti-bacterial activities of the prepared samples against two pathogenic bacteria, Escherichia coli (Gram-negative), and Staphylococcus aureus (Gram-positive) were investigated. The properties of the as-prepared samples were characterized by XRD, EDX, SEM, TEM, TGA, FT-IR, UV–Vis DRS, and BET instruments. The XRD analysis indicated that the size of crystallites was decreased for the ZnO powder prepared in the presence of the leaf extract. The SEM images showed that the samples consist of spherical shaped well-distributed particles. In addition, the presence of biomolecules from the leaf extract was revealed by EDX, TGA, FT-IR, and UV–Vis DRS analyses, which are important in biosynthesis process. The highest anti-bacterial activity belonged to the ZnO/CuO (10%) nanocomposite and the other compounds, including ZnO/CuO (5%), ZnO (ext), and ZnO (W) were in the next ranks, respectively. It was observed that the viability percentages against E. coli (10.16?±?2.2) is higher than that of S. aureus (17.1?±?0.87) in the presence of the ZnO/CuO (10%) nanocomposite. Ultimately, the mechanism for the action of the ZnO/CuO (10%) nanocomposite was explored through the SEM images, which involved the disruption of the bacterial membranes.  相似文献   
10.
Debugging—the process of identifying, localizing and fixing bugs—is a key activity in software development. Due to issues such as non-determinism and difficulties of reproducing failures, debugging concurrent software is significantly more challenging than debugging sequential software. A number of methods, models and tools for debugging concurrent and multicore software have been proposed, but the body of work partially lacks a common terminology and a more recent view of the problems to solve. This suggests the need for a classification, and an up-to-date comprehensive overview of the area. This paper presents the results of a systematic mapping study in the field of debugging of concurrent and multicore software in the last decade (2005–2014). The study is guided by two objectives: (1) to summarize the recent publication trends and (2) to clarify current research gaps in the field. Through a multi-stage selection process, we identified 145 relevant papers. Based on these, we summarize the publication trend in the field by showing distribution of publications with respect to year, publication venues, representation of academia and industry, and active research institutes. We also identify research gaps in the field based on attributes such as types of concurrency bugs, types of debugging processes, types of research and research contributions. The main observations from the study are that during the years 2005–2014: (1) there is no focal conference or venue to publish papers in this area; hence, a large variety of conferences and journal venues (90) are used to publish relevant papers in this area; (2) in terms of publication contribution, academia was more active in this area than industry; (3) most publications in the field address the data race bug; (4) bug identification is the most common stage of debugging addressed by articles in the period; (5) there are six types of research approaches found, with solution proposals being the most common one; and (6) the published papers essentially focus on four different types of contributions, with “methods” being the most common type. We can further conclude that there are still quite a number of aspects that are not sufficiently covered in the field, most notably including (1) exploring correction and fixing bugs in terms of debugging process; (2) order violation, suspension and starvation in terms of concurrency bugs; (3) validation and evaluation research in the matter of research type; (4) metric in terms of research contribution. It is clear that the concurrent, parallel and multicore software community needs broader studies in debugging. This systematic mapping study can help direct such efforts.  相似文献   
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