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1.
为缓解我国水、能源和粮食资源紧张问题,促进资源可持续利用,构建水-能源-粮食系统,利用耦合协调度模型对我国的30个省(自治区、直辖市)进行测算,并利用空间杜宾模型分析主要影响因素。结果表明:2003—2017年,我国能源、粮食评价[JP]指数高于水资源评价指数,系统综合评价指数逐年递增;大部分省份耦合协调度处于初级协调水平且呈现逐年上升的态势,个别省份耦合协调度濒临失调;耦合协调度空间自相关性较强,虽有明显波动,但是呈现逐年加强的态势;影响耦合协调度的主要因素有从业人口数、固定资产投资额、人均生产总值、人口总数、[JP]文盲人口占比、工业污染排放、城镇化。  相似文献   
2.
为准确测定气体裂变产物88Kr的半衰期,本工作从辐照铀靶中分离得到3个放化纯的88Kr气体测量源。以85Kr作内标监督源,137Cs或57Co作外标监督源,使用多个HPGe探测器分别采用单探测器位置接力法和双探测器位置接力法跟踪测量88Kr 196.3 keV能量的特征γ射线,跟踪时间均在8个半衰期以上,以获得其半衰期数据。对3次独立测量数据用多种方法进行处理,最终得到88Kr半衰期测定结果为(2.796±0.015) h。  相似文献   
3.
This paper presents a fast distance relay for series compensated transmission lines based on the R–L differential-equation algorithm using the theory of equal transfer process of transmission lines. The measuring distances based on the proposed algorithm can fast approach the actual value of fault distance when a fault occurs in front of the series capacitor. When a fault occurs behind of the series capacitor, the fault loop, including the series capacitor, does not match the R–L transmission line model, so the measuring distances fluctuate severely. Based on this, the relative position of the fault with respect to the series capacitor can be judged effectively according to the fluctuation range of the measuring distances, and the accurate fault location can be obtained fast. A variety of PSCAD/EMTDC simulation tests show that the new relay has fast operating speed and high accuracy when applied to the long series compensated transmission lines.  相似文献   
4.
Shale gas, as an important unconventional resource, has drawn global attention. It is mainly composed of adsorption gas and free gas. Adsorption gas content could play an important guiding role on both the selection of favorable perspective area and the exploration and exploitation of shale gas resources. In order to accurately measure adsorption gas content, a new approach was established to predict the adsorption isotherm of methane on shale. Based on the simplified local-density (SLD) method, both the adsorption isotherms of illite, illite/smectite mixed-layer, cholorite and type III kerogen and the total shale rock could be well fitted. The fitting results show good coincidences with the true experimental test data, which proves the method is reasonable and dependable and the prediction results are effective and credible. In addition, the good simulation results show that the SLD parameters can reflect the pore structure characteristics and corresponding adsorption characteristics of the shale samples, which can be used for the quantitative characterization of shale pore system.  相似文献   
5.
Power transformers are protected by different relays that operate independently. Malfunction of each relay has a major role in reducing the reliability of the protection system. In order to mitigate the main drawbacks of the power transformer relays, an overall protection scheme is presented in this paper. This scheme proposes a novel multi criterion algorithm using decision-making based on fuzzy logic. In this paper the outputs of restricted earth fault relay and a directional check unit, are combined with the output of the differential protection relay. Therefore, problems that are pertaining to independent operation of each relay have been mitigated and the relays cover protection blind spots of each other. The improved power transformer protection (IPTP) scheme enhances the sensitivity and reliability of the power transformer protection. Extensive simulations are used to measure the effectiveness and merit of the proposed IPTP relay. The above efforts result in a multi criteria approach for protection of power transformers.  相似文献   
6.
根据通信导航设备在雷击中的损坏现象,提出了电源防雷措施,即实施分级保护,在多雷区配置防雷变压器。简单介绍了级间配合,抑制横向过电压的产生,以及接地阻抗的简单计算和正确选用等,以达到对电源系统的有效防雷保护。  相似文献   
7.
柔性桩沉降可靠性的简化分析公式   总被引:1,自引:1,他引:0  
马克生  龚晓南 《水利学报》2001,32(2):0063-0069
本文提出了结合分层的剪切位移法、摄动法和随机场理论来计算柔性桩沉降可靠度的简化方法,并用随机有限元和蒙特卡洛模拟法对此简化模型的精度进行了对比分析,分析结果表明该方法计算简便,精度较高。通过算例发现,在土的变形模量为小变异的情况下,其概率模型对桩的沉降可靠度影响不明显,因此其概率模型可近似采用正态分布;在土的变形模量为大变异的情况下,其概率模型对桩的沉降可靠度影响非常明显,在选择概率模型时要慎重。对于土的变形模量服从对数正态分布的情况,采用将其当量正态化后的中心点法即使在参数大变异的情况下也可以获得理想的计算精度。  相似文献   
8.
对烧结成品运输自控系统不稳定性因素进行了分析,提出了采取优化硬件外围工作环境,完善软件保护程序等改进措施。改进后的自控系统稳定性明显提高。  相似文献   
9.
Large, easily viewed status boards are commonly used in some healthcare settings such as emergency departments, operating theaters, intensive care units, and inpatient wards. Because these artefacts were developed by front-line users, and have little to no supervisory or regulatory control, they offer valuable insights into the theories of work and hazard held by those users. Although the status boards case were locally developed over many years for within-group coordination, they have also become useful for between-group coordination across organizational boundaries. In this paper, we compare and contrast the use of such status boards in two disparate settings: a US emergency department, and a UK pediatric ward, and note striking similarities in their form and usage, despite the large differences in setting.  相似文献   
10.
Coordinating production and distribution of jobs with bundling operations   总被引:1,自引:0,他引:1  
We consider an integrated scheduling and distribution model in which jobs completed by two different machines must be bundled together for delivery. The objective is to minimize the sum of the delivery cost and customers' waiting costs. Such a model not only attempts to coordinate the job schedules on both machines, but also aims to coordinate the machine schedules with the delivery plan. Polynomial-time heuristics and approximation schemes are developed for the model with only direct shipments as well as the general model with milk-run deliveries.  相似文献   
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