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1.
澜沧江中下游河流泥沙特性分析   总被引:3,自引:1,他引:2       下载免费PDF全文
为了探究漫湾水库拦沙对上下游干支流河道泥沙理化特性的影响,运用激光粒度、X衍射、X荧光光谱的实验测试方法,对澜沧江中下游干流和主要支流河道的悬移质泥沙及其床沙的理化特性进行了测验.结果显示:澜沧江中下游悬移质泥沙粒径频率曲线多为单峰态,粒度范围较宽,分选性较好,床沙粒径频率曲线呈多折状且很陡,分选性差;泥沙的主要矿物组成为石英,其含量集中在60%-80%范围内;悬沙元素组分具有较好的一致性,床沙微量元素含量从旧州至界碑有下降的趋势;漫湾水库拦沙效应对泥沙的粒度,矿物组分的空间分布存在较大影响,对除硅(Si)以外的常量元素组成影响不大,对重金属元素有一定的拦截作用.研究结果可为澜沧江干流在建的多个水电站对泥沙组成的影响提供参考.  相似文献
2.
一种HFC接入网带宽拍卖分配算法   总被引:2,自引:0,他引:2  
针对HFC接入网单频点带宽合理分配以及频点组内负载均衡的问题,提出了一种基于多标拍卖的HFC接入网带宽分配算法.边缘资源管理器负责拍卖带宽资源,业务代理向其提交投标集合,采用改进的多标拍卖算法分配带宽资源.通过用户接纳控制和预留最低QoS带宽的方法保障多媒体业务的QoS.利用业务代理的用户接纳策略使频点组达到负载均衡.理论分析和实验结果表明,该算法通信开销小,时间复杂度低,能合理有效地分配带宽资源,并使频点组内达到负载均衡.  相似文献
3.
结合宾汉姆流体的流变方程与流体粘度的时变性特性,建立了考虑时变性的宾汉姆流体的流变方程与渗流运动方程,并在一些假设的基础上,推导考虑时变性的宾汉姆流体的球形及柱形渗透注浆机理,通过设计两组室内注浆试验对其进行了验证。试验结果表明:由考虑时变性的宾汉姆流体的渗透机理公式计算出的理论扩散半径与试验实际测量的扩散半径虽然有20%左右的差异,但处于可接受误差的范围内,因而在总体上能够较好地反映考虑时变性的宾汉姆流体的注浆渗透规律,对注浆设计、施工和理论研究等方面具有一定的参考价值与指导作用。  相似文献
4.
面向目标的带先验概率的AdaBoost算法   总被引:2,自引:1,他引:1       下载免费PDF全文
针对集成学习算法研究中多个分类器的最佳组合问题,改进了传统的AdaBoost集成学习算法.用于组合的各个分类器通常是基于样本集通过一定的训练得到,样本集中不同类目标的比率可以反映分类目标的先验概率.使用该参数给出了新的组合参数和投票表决阈值计算公式,巧妙的利用样本权值并将其加入到样本属性上进行训练学习,采用新的策略来选择基分类器,给出了面向目标的带先验概率的AdaBoost算法(GWPP AdaBoost算法)和分类器的最佳组合.依据UCI实验数据对传统的AdaBoost算法、Bagging算法、GWPP AdaBoost算法的错误率和性能进行了比较分析,验证了GWPP AdaBoost的有效性.  相似文献
5.
地震作用下折线型滑面斜坡的动力响应   总被引:1,自引:0,他引:1  
折线型滑面斜坡是一种常见的滑坡类型,在地震作用下的动力响应非常复杂。为了研究地震作用下折线型滑面斜坡的动力响应,应用动力响应时程分析法,利用大型有限元软件ANSYS建立了数值模型。首先分析了模型在静力作用下的力学特性,然后对模型输入地震波,分析模型在动力作用下的动力响应。通过分析得到,斜坡在地震动力作用下出现了应力转移,节理上下两侧岩层发生错动,由于锁固段的存在,斜坡下部错动大于上部。研究斜坡属于后发型滑坡,地震作用虽未使斜坡发生破坏,但由于地震作用的累积效应,使斜坡的稳定性降低。  相似文献
6.
In order to simplify the design of the film thickness of the film bulk acoustic resonator, a design method for film bulk acoustic resonator film thickness is proposed. The simulation structure consists of the induced layer and the upper electrode-piezoelectric-electrode sandwich structure. The initial film of the film bulk acoustic resonator is designed by the optimal effective electromechanical coupling coefficient, and then the thickness of the induced layer and the corresponding frequency offset value are determined. The parallel resonant frequency is compensated with the frequency offset, and then the film thickness of the electrode and the piezoelectric are recalculated. Finally, the structure is simulated by COMSOL. When the parallel resonant frequency is 3.60 GHz, the frequency offset value of the 100 nm AlN is 0.20 GHz. The effective electromechanical coupling coefficient of the AlN is 5.907%. After frequency compensation, the series resonant frequency and parallel resonant frequency of the AlN are 3.48 GHz and 3.60 GHz, respectively. The design method is verified. The induced layer effectively optimizes the C-axis characteristics of the piezoelectric layer and reduces energy loss.  相似文献
7.
In order to save the power consumed by the static random access memory when it deals with voice or video data, a novel memory cell is proposed which eliminates the precharge mechanism in the read operation, thus suppressing the invalid power compared with the conventional 6T and 8T cell. Furthermore, multiple threshold technology is employed in the cell, which not only guarantees the read static noise margin, but also enhances read ability. In addition, a Schmitt trigger based inverter is also applied in the cell array and hence it improves the read speed. Two memories including the proposed one and the conventional one are fabricated in 130nm process, respectively. Test results indicate that the proposed memory is excellent in reducing power consumption compared with the conventional 8T memory, and hence it becomes a suitable choice for the low power chips.  相似文献
8.
An adaptable feedback tuning algorithm based on the analyses of various phase detection mechanisms and filter architectures is presented to shorten the locking time of all-digital phase-locked loops (ADPLLs). The algorithm divides the entire locking processes into coarse tuning, first fine tuning and second fine tuning processes corresponding to control codes of coarse, first and second fine stages in the digitally controlled oscillator (DCO). An appropriate filter architecture is chosen in each process while adaptive factors are tunable according to the value of the frequency error. A portable fast-locking fractional-N ADPLL based on the proposed algorithm is fabricated by 180nm CMOS technology. Measurement shows that the average locking time is only 6.4μs, that is, 128 reference cycles with a 20MHz clock. The locking time is reduced by the algorithm effectively.  相似文献
9.
The magnetic modulation zero-flux current sensor, with its excellent characteristics, is widely used in both power supply and power consumption equipment. The rapid developments of the smart grid and big data lead to a remarkable increase in the demand for monitoring the working status of the sensor. To obtain the state feature information of the current sensor, this paper proposes a magnetic modulation analysis method based on the fact that the permeability of ferromagnetic materials varies with the strength of the magnetic field (or current). This method not only circumvents the shortcomings of magnetic modulation with trilinear analysis, but also is able to obtain clear relations among all parameters. Based on the fundamental principle of the zero-flux, the Fourier series is employed to analyze the frequency components carried by modulation and demodulation signals. By comparing the spectrum of modulation and demodulation signals with both zero and non-zero flux, the relevant frequency components indicating the working status of magnetic modulation are determined. According to the working principle of the zero-flux current sensor, a basic method is proposed to judge the working status of the magnetic-modulation-style zero-flux current sensor. The relation between the magnetic modulation feature information and the working status of the zero-flux current sensor is validated with real circuits, and the experimental results coincide with the inference.  相似文献
10.
A frequency calibration technique with the hybrid calibration process is proposed to reduce the calibration time of the voltage-controlled oscillator (VCO) and maintain the fine calibration resolution. The calibration technique begins by employing the relative frequency comparison method to discern and decrease the difference between the frequency tuning curve and the target frequency. When the frequency tuning curve is close to the target frequency, the calibration technique changes to utilize the frequency error detection method to achieve a fine calibration resolution. With the fast relative frequency comparison process and the high-accuracy frequency error detection process, the calibration time for a frequency resolution of 2MHz is only 2.77μs. Compared to the conventional binary searcher process by only employing the frequency error detection method, the proposed technique saves 31% of the calibration time under the same calibration resolution. Furthermore, this calibration technique is suitable for the wideband fractional-N frequency synthesizer.  相似文献
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