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排序方式: 共有4562条查询结果,搜索用时 15 毫秒
1.
Fast DCT algorithm with fewer multiplication stages 总被引:1,自引:0,他引:1
Yeonsik Jeong Imgeun Lee Hak Soo Kim Kyu Tae Park 《Electronics letters》1998,34(8):723-724
A novel fast DCT scheme with reduced multiplication stages and fewer additions and multiplications is proposed. The proposed algorithm is structured so that most multiplications tend to be performed at the final stage, which reduces the propagation error that could occur in the fixed-point computation. Minimisation of the multiplication stages can further decrease the error 相似文献
2.
In this study, an aluminum based metallic matrix (Al-2wt.% Cu) was reinforced with SiC particulates using a conventional casting technique and a new disintegrated melt deposition technique. Microstructural characterization studies conducted on the samples taken from disintegrated melt deposition technique revealed a more uniform distribution of SiC particulates and good interfacial integrity between SiC particulates and metallic matrix when compared to the conventionally cast composite samples. Results of ambient temperature mechanical tests demonstrate an increase in 0.2% YS and ultimate tensile strength of samples taken from disintegrated melt deposition technique when compared with the unreinforced and conventionally cast composite samples. The results of microstructural characterization and mechanical testing were finally rationalized in terms of the nature of processing technique employed to reinforce Al-2wt.% Cu metallic matrix with SiC particulates. 相似文献
3.
MJ Glantz PC Burger AH Friedman RA Radtke EW Massey SC Schold 《Canadian Metallurgical Quarterly》1994,44(11):2020-2027
When radiation is used to treat nervous system cancer, exposure of adjacent normal nervous system tissue is unavoidable, and radiation-induced injury may occur. Acute injury is usually mild and transient, but late forms of radiation-induced nervous system injury are usually progressive and debilitating. Treatment with corticosteroids, surgery, and antioxidants is often ineffective. We treated 11 patients with late radiation-induced nervous system injuries (eight with cerebral radionecrosis, one with a myelopathy, and two with plexopathies, all unresponsive to dexamethasone and prednisone) with full anticoagulation. Some recovery of function occurred in five of the eight patients with cerebral radionecrosis, and all the patients with myelopathy or plexopathy. Anticoagulation was continued for 3 to 6 months. In one patient with cerebral radionecrosis, symptoms recurred after discontinuation of anticoagulation and disappeared again after reinstitution of treatment. We hypothesize that anticoagulation may arrest and reverse small-vessel endothelial injury--the fundamental lesion of radiation necrosis--and produce clinical improvement in some patients. 相似文献
4.
In this report the effects of single doses of ionizing radiation on the mRNA expression of several proteins involved in multiple drug resistance were analyzed. Murine NIH 3T3 cells treated with single doses of 5, 10 and 20 Gy during the time interval from 1.5 to 72 h after irradiation were compared with their corresponding controls at the same points of time. The glutathione S-transferase-pi (GST pi) level was elevated in cells treated with 10 or 20 Gy from 24 to 72 h after irradiation compared with the control. Topoisomerase II alpha and thymidylate synthase were decreased in irradiated cells 24-72 h after exposure. These down-regulations were associated with cellular proliferation, determined by mRNA expression of the proliferation marker histone 3. Irradiated cells exhibited no alteration in the P-glycoprotein or glutathione peroxidase mRNA content. The finding that GST pi mRNA was overexpressed after irradiation was validated by investigations on a human lung carcinoma cell line (LXF 289) on the mRNA and protein level. Thus, our results indicate that irradiation alters the expression of proteins involved in multidrug resistance and may, therefore, play a role in clinical drug response. 相似文献
5.
Kwang Soo Lee In Soo Park & Dong Sun Lee 《International Journal of Food Science & Technology》1996,31(1):7-13
The aim of this study was to design a modified atmosphere package for a mixed vegetable salad consisting of 75 g of cut carrot, 55 g of cut cucumber, 20 g of sliced garlic and 50 g of whole green pepper. Respiration data of all the components were combined with film permeability data to predict package atmospheres and design optimal packages for experimental testing for improved shelf-life of the produce. The optimal package avoided minimum O2 and maximum CO2 tolerance limits, and chilling injury temperatures for any component. A pouch form package made of 27 mm low density polyethylene developed a modified atmosphere of 2.0–2.1% O2 and 5.5–5.7% CO2 , which was beneficial for all components and provided better quality retention than other test packages. 相似文献
6.
Measurements of local velocity, density, and mass flow of phases of a gas-solid suspension are needed in determining transport properties, validating theoretical predictions, and formulating design procedures. Most of the available instruments are based on time averages or fluctuations with time. Primary standard for direct measurement of density of a phase such as solid particles is being developed. A laser phase Doppler device, within certain restrictions, may give local instantaneous density, while other optical methods and neutron beam remain secondary standards based on mass flow calibrations. An overall review including recent results has been made on both intrusive and non-intrusive instruments; their limitations and future possibilities are outlined and discussed. The limitations of the traditional approach utilizing the triangular relation between local averages of mass flow, velocity, and density of particles for the determination of flow properties, and higher order correlations are demonstrated. 相似文献
7.
Hyeong Soo Chang 《Automatic Control, IEEE Transactions on》2005,50(9):1413-1418
This note considers finite-step approximations for solving an infinite-horizon controlled Markov set-chain problem with finite state and action spaces. We develop a value-iteration type algorithm based on the optimality equation developed by Kurano et al. and analyze an error bound relative to the optimal value that satisfies the optimality equation from the successive approximation. We further analyze an error bound of the approximate control policy defined from a finite-step approximate value by applying the value-iteration type algorithm. 相似文献
8.
9.
Public participation is essential in each step of the nuclear-related decision-making process. Recently, the electronic systems using the Internet have become quite popular, and have emerged as a good medium for communicating with the public. In this study, a comprehensive utilization of electronic public participation was used to analyze public opinion on a given nuclear-related decision-making process. The degree of deliberation and meditation of the public participating in an electronic poll survey was evaluated, and the decision-making factors representing the personal characteristics of the poll respondents such as age, income, education, residence, degree of knowledge and concern were carefully incorporated when preparing the poll-survey questionnaire for its evaluation. Fuzzy analysis was used to assess and aggregate the responses to each decision-making factor. As a case study, this procedure was used to analyzing public opinion on the location of a low-level radioactive waste disposal facility on the campus of Seoul National University. The results show that there is a tendency of respondents who are on the negative side of the argument to be more deliberate and meditative in their decision-making process than those on the positive side. Knowledge and residence were found to be important decision-making factors. 相似文献
10.
This paper proposes a new LDMOSFET structure with a trenched sinker for high‐power RF amplifiers. Using a low‐temperature, deep‐trench technology, we succeeded in drastically shrinking the sinker area to one‐third the size of the conventional diffusion‐type structure. The RF performance of the proposed device with a channel width of 5 mm showed a small signal gain of 16.5 dB and a maximum peak power of 32 dBm with a power‐added efficiency of 25% at 2 GHz. Furthermore, the trench sinker, which was applied to the guard ring to suppress coupling between inductors, showed an excellent blocking performance below ?40 dB at a frequency of up to 20 GHz. These results confirm that the proposed trenched sinker should be an effective technology both as a compact sinker for RF power devices and as a guard ring against coupling. 相似文献