On recommendation problems beyond points of interest

Recommendation systems aim to recommend items or packages of items that are likely to be of interest to users. Previous work on recommendation systems has mostly focused on recommending points of interest (POI), to identify and suggest top-k items or packages that meet selection criteria and satisfy compatibility constraints on items in a package, where the (packages of) items are ranked by their usefulness to the users. As opposed to prior work, this paper investigates two issues beyond POI recommendation that are also important to recommendation systems. When there exist no sufficiently many POI that can be recommended, we propose (1) query relaxation recommendation to help users revise their selection criteria, or (2) adjustment recommendation to guide recommendation systems to modify their item collections, such that the users׳ requirements can be satisfied.We study two related problems, to decide (1) whether the query expressing the selection criteria can be relaxed to a limited extent, and (2) whether we can update a bounded number of items, such that the users can get desired recommendations. We establish the upper and lower bounds of these problems, all matching, for both combined and data complexity, when selection criteria and compatibility constraints are expressed in a variety of query languages, for both item recommendation and package recommendation. To understand where the complexity comes from, we also study the impact of variable sizes of packages, compatibility constraints and selection criteria on the analyses of these problems. Our results indicate that in most cases the complexity bounds of query relaxation and adjustment recommendation are comparable to their counterparts of the basic recommendation problem for testing whether a given set of (resp. packages of) items makes top-k items (resp. packages). In other words, extending recommendation systems with the query relaxation and adjustment recommendation functionalities typically does not incur extra overhead.     

调整我国产业结构的若干思考

在国有企业产权制度改革中，改革不合理的产业结构是主要内容之一。不合理的产业结构带来了资产流量与存量产出效益的巨大损失，并放大了市场信号的失真度。因此强化产业结构的调整，是深化经济体制改革，使国民经济持续发展的保证。本文在分析产业结构不合理现状的基础上，提出了对调整我国产业结构的见解。     

塔里木油田水平井优化设计方法及跟踪效果评价

塔里木油田坚持“稀井高产”的开发原则,不仅利用水平井技术实现了新油田整体高效开发,而且在老油田综合调整中也取得了巨大成效,还成功应用于气藏及凝析气藏的开发,以水平井技术为主实现了气田开发高水平和高效益,逐渐形成了一套比较成熟的适合塔里木气区实际的水平井优化设计技术。 \r\n     

试论大型汽车覆盖件模具制造调试的途径

针对汽车大型覆盖件零件的工艺特点，采用先进的模拟仿真技术、测量技术、调试技术、逆向工程技术，探索出了一条汽车大型覆盖件模具制造调试的途径。     

临盘油区复杂断块油藏有效的开发治理技术

针对临盘油区地质条件的复杂性和开发调整的困难度,本文阐述了复杂断块油藏开发治理技术的应用,如精细地质研究技术、剩余油研究技术以及改善水驱油效果的注采调整技术等。精细地质研究技术深化了对油藏的认识程度;剩余油研究技术深化认识不同类型油藏剩余油分布规律,明确了注采调整方向;针对不同类型油藏具有的不同潜力,创新注采调整思路,不断优化注采井网,改善了油藏的开发效果。     

螺旋缠绕厚壁压力容器封头段的线型调整

给出螺旋缠绕厚壁压力容器封头段纤维层厚度的计算公式以及线型调整的基本方法 ,通过调整线型 ,以达到螺旋缠绕厚壁压力容器封头段既不滑线又满足封头段强度要求的目的     

乙烯装置三机的自动控制系统

系统地介绍乙烯装置三机的自动控制系统，包括油系统、气系统和工艺系统的控制，并对运行以来发生的主要故障进行了分析，最后对控制系统发展的前景进行了展望。     

基于模拟退火算法的电力系统输电阻塞成本控制

研究了实时电力系统中输电阻塞管理的成本控制问题.针对同时开放发电侧和负荷侧的情形,引入阻塞率因子,建立了新的阻塞费用优化模型.基于minimax思想和模拟退火算法,将实时阻塞管理问题转化为最大输电阻塞时调整费用最小的非线性规划问题,得到了全局最优解.仿真结果表明,改进的优化模型可有效缩减和控制调整费用,所设计的算法简单可行且安全可靠.     

八面河油田油井节能工作的实践与效果

节能降耗是提高企业经济效益,增强企业竞争力的重要措施。八面河油田针对稠油区块机采系统效率低、部分油井工况优化余地大、机采设备整体利用率低等能耗问题,提出了如下治理对策:1、在设备节能改造方面,推广低冲次稠油节能抽油机和节能永磁电机。2、在改善油井工况方面,合理油井沉没度,加强偏磨腐蚀治理,降低油井无效排液。3、结合区块特点,加大调整稀油区块及稠油区块与百米吨液耗电的平衡力度。     

冷床升降横梁的定位及链条调整机构改进

针对冷床频繁出现的故障情况，分析链条脱落、卡死及拉断的原因、增设升降横梁定位装置，改进链条调整装置，消除故障。