Continuous space maximal coverage: Insights,advances and challenges

Siting facilities in continuous space to maximize coverage of regional demand is an important planning problem. It is challenging to solve because demand is continuously distributed in a region and facilities may be sited anywhere in the region, suggesting that an infinite number of locations must be considered both as demand for service as well as a potential facility. An ingenious approach for solving continuous space coverage problems is abstracting continuously distributed demand as discrete spatial objects (points, lines or polygons), generating a finite dominating set from continuous space as candidate facility sites, and applying a discrete location coverage model. However, abstracting continuous demand and potential facility sites often introduces errors and uncertainties in coverage of regional demand, rendering findings (service and optimal facility locations) less than definitive. In this paper we examine the continuous space maximal coverage problem. Studies focused on locating antennas in Paradise Valley, Arizona and emergency warning sirens in Dublin, Ohio, are used to highlight issues and challenges in continuous space modeling. Potential paths forward are suggested based on empirical insights.     

Deterministic and probabilistic ship pitch prediction using a multi-predictor integration model based on hybrid data preprocessing,reinforcement learning and improved QRNN

The deterministic and probabilistic prediction of ship motion is important for safe navigation and stable real-time operational control of ships at sea. However, the volatility and randomness of ship motion, the non-adaptive nature of single predictors and the poor coverage of quantile regression pose serious challenges to uncertainty prediction, making research in this field limited. In this paper, a multi-predictor integration model based on hybrid data preprocessing, reinforcement learning and improved quantile regression neural network (QRNN) is proposed to explore the deterministic and probabilistic prediction of ship pitch motion. To validate the performance of the proposed multi-predictor integrated prediction model, an experimental study is conducted with three sets of actual ship longitudinal motions during sea trials in the South China Sea. The experimental results indicate that the root mean square errors (RMSEs) of the proposed model of deterministic prediction are 0.0254°, 0.0359°, and 0.0188°, respectively. Taking series #2 as an example, the prediction interval coverage probabilities (PICPs) of the proposed model of probability predictions at 90%, 95%, and 99% confidence levels (CLs) are 0.9400, 0.9800, and 1.0000, respectively. This study signifies that the proposed model can provide trusted deterministic predictions and can effectively quantify the uncertainty of ship pitch motion, which has the potential to provide practical support for ship early warning systems.     

多运营商高铁隧道移动网络覆盖方案

高铁移动网络覆盖是国内三大通信运营商的一个重点,而高铁隧道内移动网络覆盖更是运营商的一大难点痛点。文章根据我国中部省份某高铁线路覆盖规划实例,采用“设备+POI+泄漏电缆”模式,即三家运营商信号源设备通过同一POI(point of interface,多系统接入平台)接入,信号输出到泄漏电缆进行隧道覆盖,隧道口场坪站安装宽频切换天线对隧道外进行延伸覆盖,通过链路预算合理布置各运营商主设备信号源,从而实现隧道到室外的无缝覆盖。最后,根据已有成熟网络覆盖解决方案,对未来5G高铁隧道移动网络覆盖方案进行了探讨。     

浅析我国企业年金发展的必要性和存在的问题

论述了企业年金是企业为职工设立的一种介于国家基本养老保险与个人商业养老保险之间的补充性养老保险制度,企业年金的顺利发展关系到社会的稳定、国家的和谐发展,是人们普遍关心的问题。     

肇庆东雅苑一期园林环境的设计与施工实践

东雅苑在有限的绿地空间中，突破了以往的绿化种植模式，构建高效益的复合植物群落。各个景区具有鲜明的主题和构思特点，融观赏性、娱乐性、趣味性和服务性于一体，受到了房地产商和业主们的欢迎和认可。     

一种改良的射线追踪模型原理及应用效果验证

本文对现有先进的射线追踪模型及相关参数和算法进行了详细分析，并基于湖南移动现在使用的模型算法，通过具体不同参数的设置及现场测试验证，分析仿真与真实情况的差异，根据测试结果给出最优的模型及相关参数。     

Removing divergence of JCGM documents from the GUM (1993) and repairing other defects

The mission of the Joint Committee for Guides in Metrology (JCGM) is to maintain and promote the use of the Guide to the Expression of Uncertainty in Measurement (GUM) and the International Vocabulary of Metrology (VIM, second edition). The JCGM has produced the third edition of the VIM (referred to as VIM3) and a number of documents; some of which are referred to as supplements to the GUM. We are concerned with the Supplement 1 (GUM-S1) and the document JCGM 104. The signal contribution of the GUM is its operational view of the uncertainty in measurement (as a parameter that characterizes the dispersion of the values that could be attributed to an unknown quantity). The operational view promulgated by the GUM had disconnected the uncertainty in measurement from the unknowable quantities true value and error. The GUM-S1 has diverged from the operational view of the uncertainty in measurement. Either the disparities should be removed or the GUM-S1 should not be referred to as a supplement to the GUM. Also, the GUM-S1 has misinterpreted the Bayesian concept of a statistical parameter and the VIM3 definitions of coverage interval and coverage probability are mathematically defective. We offer practical suggestions for revising the GUM-S1 and the VIM3 to remove their divergence from the GUM and to repair their defects.     

Trajectory segment selection with limited budget in mobile crowd sensing

Mobile Crowd Sensing is an emerging paradigm, in which a large number of participants are involved to complete a sensing task under a certain incentive mechanism. Hence, when the budget used to pay participants is limited, how to choose the most appropriate participants becomes a critical problem. Most of existing works aim to select a subset of participants to maximize the coverage, without considering redundancy. There are two kinds of redundancy in the existing literature, one is brought by the incomplete coverage assessment, while the other one is brought by the traditional participant selection process. Since paying for redundant data leads to budget waste, existing works cannot solve the participant selection problem commendably under limited budget. To address such issues, we first propose a coverage assessment considering both uniform coverage and maximum coverage, then design a trajectory segment selection scheme. Rather than choosing the whole trajectory of a participant, our scheme selects certain segments. Both offline and online algorithms are proposed in this paper. Two benchmarks are implemented and we carry out extensive experiments based on a real dataset. The evaluation results prove the effectiveness and the advantage of our algorithms in terms of the coverage quality.     

Photovoltaic system assessment for a school building

The installation of photovoltaic panels (PVs) on the roof of residential and commercial buildings is getting widespread as these areas stand normally idle and can be used for another purpose without losing an inhabited space. Considering the solar potential of Turkey, a significant amount of electricity generation is possible using current PV technology. For this reason, a two-story detached school building located in ?zmir, Turkey was taken into consideration and monthly as well as annual coverage ratio of an on-grid PV system for its entire energy requirement (including heating, cooling and lighting) was investigated. The PVs were installed on the south face of the school building roof. A heat pump, with a typical coefficient of performance (COP) value of 2.5, was used for supplying required cooling and heating. The heating, cooling and lighting loads were determined on a monthly basis. The average monthly electrical energy generation of the mounted PVs was calculated using a written code in Energy Equation Solver (EES) software. As a result, the monthly as well as yearly electrical energy demand coverage ratio values for the school using the installed PVs were revealed. Since the school building has a large south faced roof, the installation of PVs is very suitable to meet the cumulative electrical energy need of the heat pump and the lighting load. For Case 1, 180 PVs, which supply the entire yearly demand (with a 110% coverage ratio), were taken into consideration, while for Case 2, 265 PVs, which cover 75% of the roof area, were evaluated. The results showed that between November and March, PV electrical energy generation is not sufficient to meet all energy need of the school for both cases. However, significant coverage ratio values were observed for the rest of the year. In a yearly basis, the PV generation exceeded the building demand by 62% for the Case 2. This conclusion points out that the school can meet its yearly electricity need with the considered PV system and can even have an additional financial profit by selling its surplus PV electricity to the grid. Economic and environmental payback time values as well as simple payback time value were also computed for both investigated cases. The results pointed out a simple payback time of 7.9 years for Case 1 and 7.6 years for Case 2. Energy payback time was determined as 5 years for both systems. The greenhouse gas payback time of 2.7 years and 5.9 years was encountered for coal based and natural gas based calculations.