排序方式: 共有62条查询结果,搜索用时 15 毫秒
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Seyed Mehdi Rezaei Farshad Barazandeh Mohammad S. Haidarzadeh Seid M. Sadat 《Journal of Intelligent and Robotic Systems》2010,59(3-4):299-318
Most of the research conducted on snake robots has been on movement, control or dynamics. There is only some research dealing with the reduction of actuators’ sizes. Actuator size usually depends on the force/torque it can provide. Small actuators imply a more efficient, long lasting, lighter and more flexible robot. The required force/torque and energy consumption consequently is directly affected by the mechanism design. Mother nature has always presented optimum systems and has inspired engineers. In this paper, we have adopted the snake anatomy to design a snake robot. The results show a reduction in torque demand. This robot is an extension of our previous research on building a snake without including the anatomy. The new robot weighs about only one-third of the previous version. 相似文献
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Jebril S Elbahri M Titazu G Subannajui K Essa S Niebelschütz F Röhlig CC Cimalla V Ambacher O Schmidt B Kabiraj D Avasti D Adelung R 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(12):2214-2221
One-step device fabrication through the integration of nanowires (NWs) into silicon microchips is still under intensive scientific study as it has proved difficult to obtain a reliable and controllable fabrication technique. So far, the techniques are either costly or suffer from small throughput. Recently, a cost-effective method based on thin-film fracture that can be used as a template for NW fabrication was suggested. Here, a way to integrate NWs between microcontacts is demonstrated. Different geometries of microstructured photoresist formed by using standard photolithography are analyzed. Surprisingly, a very simple "stripe" geometry is found to yield highly reproducible fracture patterns, which are convenient templates for fault-tolerant NW fabrication. Microchips containing integrated Au, Pd, Ni, and Ti NWs and their suitability for studies of conductivity and oxidation behavior are reported, and their suitability as a hydrogen sensor is investigated. Details of the fabrication process are also discussed. 相似文献
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Seid Koric Lance C. Hibbeler Rui Liu Brian G. Thomas 《Numerical Heat Transfer, Part B: Fundamentals》2013,63(6):371-392
Separate three-dimensional (3-D) models of thermomechanical behavior of the solidifying shell, turbulent fluid flow in the liquid pool, and thermal distortion of the mold are combined to create an accurate multiphysics model of metal solidification at the continuum level. The new system is applied to simulate continuous casting of steel in a commercial beam-blank caster with complex geometry. A transient coupled elastic-viscoplastic model [1] computes temperature and stress in a transverse slice through the mushy and solid regions of the solidifying metal. This Lagrangian model features an efficient numerical procedure to integrate the constitutive equations of the delta-ferrite and austenite phases of solidifying steel shell using a fixed-grid finite-element approach. The Navier-Stokes equations are solved in the liquid pool using the standard K–? turbulent flow model with standard wall laws at the mushy zone edges that define the domain boundaries. The superheat delivered to the shell is incorporated into the thermalmechanical model of the shell using the enhanced latent heat method [2]. Temperature and thermal distortion modeling of the complete complex-shaped mold includes the tapered copper plates, water cooling slots, backing plates, and nonlinear contact between the different components. Heat transfer across the interfacial gaps between the shell and the mold is fully coupled with the stress model to include the effect of shell shrinkage and gap formation on lowering the heat flux. The model is validated by comparison with analytical solutions of benchmark problems of conduction with phase change [3], and thermal stress in an unconstrained solidifying plate [4]. Finally, results from the complete system compare favorably with plant measurements of shell thickness. 相似文献
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Several scheduling techniques exist in literature based on continuous time representation. The models based on unit specific time points have shown better solution efficiency by reducing the number of time points and problem size. In this paper novel scheduling techniques based on unit specific time point continuous time representation are presented. The proposed models allow nonsimultaneous material transfer into a unit. Nonsimultaneous transfer refers to when a task requires more than one intermediate state it is possible for one state to be transferred and stored in a unit that is processing it for a while and wait for the other intermediates to come together to start the task. This approach gives a better schedule as compared to most published models. The developed MILP scheduling models are based on state sequence network representation that has proven to inherently result in smaller problems in terms of binary variables. The models require a smaller number of time points as compared to single-grid and multi-grid continuous time models. Consequently, they exhibit much better computational performance. Numerical evaluation using literature examples indicate in some of the complex examples that the proposed models give a better objective value as compared to other scheduling models. An added feature of the proposed models is their ability to exactly handle fixed intermediate storage operational philosophy, which has proven to be a subtle drawback in most published scheduling techniques. 相似文献
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Impact of Wall Materials on Physicochemical Properties of Microencapsulated Fish Oil by Spray Drying
Parastoo Pourashouri Bahare Shabanpour Seid Hadi Razavi Seid Mahdi Jafari Ali Shabani Santiago P. Aubourg 《Food and Bioprocess Technology》2014,7(8):2354-2365
The aim of the present study was to investigate the effect of wall materials composition on physicochemical characteristics of fish oil microcapsules produced by spray drying (180 °C). Four different combination of coating materials (fish gelatin, chitosan, combination of gelatin and chitosan, and a mixture of microbial transglutaminase (MTGase) with maltodextrin) were applied to two different fish oils to produce 40 % solid emulsions. Scanning electron microscopy and extraction of surface and encapsulated oils revealed that fish gelatin provided the highest preserving effect on the covering fish oil. Meantime, addition of MTGase to gelatin could also increase this ability and reveled less surface oil than chitosan treatment (2.63 and 2.80 % versus 4.66 and 5.23 %, respectively; P?<?0.05). Mixture of gelatin and maltodextrin with MTGase as wall material led to the highest encapsulation efficiency, being selected as the best microencapsulation condition; meantime, application of chitosan with maltodextrin provided the worse encapsulation efficiency (P?<?0.05). All indices of powders (encapsulation efficiency, surface morphology, and particle size) showed that powders prepared from gelatin and gelatin with MTGase increased the encapsulation efficiency and would increase the stability of microcapsule powders. 相似文献
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This paper presents a mathematical technique for prediction of the optimal number of time points in short-term scheduling of multipurpose batch plants. The mathematical formulation is based on state sequence network (SSN) representation. The developed method is based on the principle that the optimal number of time points depends on how frequent the critical unit is used throughout the time horizon. In the context of this work, a critical unit refers to a unit that is most frequently used and it is active for most of the time points when it is compared to other units. A linear model is used to predict how many times the critical unit is used. In conjunction with knowledge of recipe, this information is used to determine the optimal number of time points. The statistical R2 value obtained between the predicted and actual number of optimal time points in all the problems considered was 0.998, which suggests that the developed method is accurate in determining optimal number of time points. Consequently this avoids costly computational times due to iterations. In the model by Majozi and Zhu (2001) the sequence constraint that pertains to tasks that consume and produce the same state, the starting time of the consuming task at time point p must be later than the finishing time of the producing task at the previous time point p?1. This constraint is relaxed by the proposed models if the state is not used at the current time point p. This relaxation gives a better objective value as compared to previous models. An added feature of the proposed models is their ability to exactly handle fixed intermediate storage (FIS) operational philosophy, which has proven to be a subtle drawback in published scheduling techniques. 相似文献
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Mahdi Shavandi Mahdi Kashaninejad Alireza Sadeghi Seid Mahdi Jafari Mahdiyeh Hasani 《Journal of Food Safety》2020,40(1):e12730
In this work, infrared (IR) irradiation was used for inactivation of Bacillus cereus in cardamom seeds. The effect of IR power (100, 200, and 300 W), sample distance from radiation source (5, 10, and 15 cm) and holding times (0–11 min) was investigated on B. cereus count, as well as cardamom seeds color and temperature profiles. Inactivation of B. cereus on cardamom seeds during IR processing was demonstrated by experimental models. The highest reduction of B. cereus count (5.11 Log CFU/g) was achieved after 8 min IR irradiation at 300 W power and 15 cm distance. Measurement of temperature profiles revealed that there was a significant difference (p < .05) between surface and center temperatures of the cardamom seeds. The green color (a* value) of cardamom seeds was slightly affected and the highest color change was observed at 200 W IR, 10 cm distance and 10 min irradiation that resulted in an increase of a* from −3.05 ± 0.96 to −0.05 ± 0.44. In conclusion, IR irradiation could be successful for decontamination of cardamom seeds without severe alteration of its quality. Among the experimental models for microbial inactivation during IR processing, the Double Weibull model had the highest coefficient value of determination (R2 = 0.9966). 相似文献