Why do people purchase virtual goods? A uses and gratification (U&G) theory perspective

Few literature studies have investigated the relationships between different uses and gratifications (U&Gs) of mobile instant messaging (MIM) apps, continuation, and purchase intentions. To address this gap, the researchers aimed to examine the influence of the content, social, process, and technology U&Gs of MIM on continuation intentions toward MIMs, and purchase intentions toward virtual goods available on MIMs. A comprehensive research model was developed based on the U&G theory, which was tested using cross-sectional data from 309 Japanese MIM users. The study considered six different U&Gs of MIM as independent variables and purchase intentions towards stickers and continuation intentions towards MIM as dependent variables. The study results suggest that exposure U&G has a significant positive association with MIM sticker purchase intentions. The entertainment and affection U&G are positively associated with continuation intentions towards MIM use. The study contributes to the literature by investigating U&Gs that motivate MIM users to have both positive purchase intentions toward virtual goods, such as stickers, and continuation intentions toward MIMs. The study has significant theoretical and practical implications for both researchers and practitioners who are interested in virtual goods, the virtual economy, MIM apps, social media, new media, and the service economy.     

Voltage stability monitoring of power systems using reduced network and artificial neural network

This paper presents network reduction based methodologies to monitor voltage stability of power systems using limited number of measurements. In a multi-area power system, artificial neural networks (ANNs) are used to estimate the loading margin of the overall system, based on measurements from the internal area only. Information regarding the important measurements from the external areas is considered in measurement transformation through the network reduction process, to enhance the estimation accuracy of the ANNs. A Z-score based bad or missing data processing algorithm is implemented to make the methodologies robust. To account for changing operating conditions, adaptive training of the ANNs is also suggested. The proposed methods are successfully implemented on IEEE 14-bus and 118-bus test systems.     

Robustness of declarative modeling languages: Improvements via probability-one homotopy

Robustness issues with steady-state initialization remain a barrier in the practical use of declarative modeling languages for multi-domain modeling of large, complex, and heterogeneous technical systems. The objective of this paper is to illustrate how probability-one homotopy, an established method from topology, can solve this issue. This is achieved by establishing a framework for application-specific probability-one homotopy in declarative modeling languages. The analysis is based on domain-specific probability-one homotopy maps, which were reformulated in a declarative fashion. Additionally, a novel probability-one homotopy map and associated coercivity proof is introduced for a class of thermo-fluid dynamics problems. It was found that the approach enables robust initialization for declarative modeling languages on several test cases and leads to a concise declarative problem formulation.     

Using PV and QV curves with the meaning of static contingency screening and planning

This paper investigates the use of the QV and PV curves in the planning scenario, when some system reinforcements and contingency screening are analyzed. The idea is to employ the continuation method to obtain the system load margin and the QV curve to calculate the reactive power reserve associated with each bus. Combining these approaches enables one to identify the system critical area, the actual operating conditions, the most severe contingencies and the most important reinforcements. The methodology proposed may provide important signals to system planners, since the planning is focused under the voltage security point of view. The ideas are tested with the help of some academic systems and two real (a Brazilians and a Paraguayan) systems with all the system limits considered.     

求一般6－SPS并联机器人机构的全部位置正解

研究了上下平台均不为平面的一般一般６－ＳＰＳ并联机器人机构的位置正解问题。首先建立了含６个变量的位置正解方程组，然后采用四元齐次化法，跟踪９６０条同伦路径，求出了其全部４０组位置正解。     

Stereo and motion correspondences using nonlinear optimization method

This paper presents a new approach for using stereo and motion correspondences to solve the problem of tracking multiple independently moving features. In this approach, quantitative relational structure (QRS) is proposed as a framework for the integration of stereo–motion correspondences. The similarity function, tightly coupled to stereo and motion cues, is constructed on QRS, and then energy function E² consisting of the similarity function is defined. The tracking problem can be converted into the maximization problem of the energy function E². The stereo and motion correspondences that maximize E² are recovered by applying an extended graduated assignment algorithm. The relaxation labeling method is also presented for the comparison with the proposed method. Experimental results are presented to illustrate the performance of the proposed method.     

一种线路极限传输容量的在线计算方法

提出了一种电力系统在线极限传输容量的计算模型和实用化算法。这一模型基于发电计划和短期负荷预测来定义负荷发电增长方向，全面地考虑了系统在一个预想故障集下的暂态稳定约束、静态稳定约束、电压和支路潮流等静态运行约束。文中采用了一种考虑暂态稳定约束的连续潮流算法来求解，在充分利用连续潮流可以有效地计及静态稳定和安全约束的同时，采用快速时域仿真技术来处理暂态稳定约束。对一个300节点的实际系统和50个故障组成的故障集的应用表明，文中所提模型和算法是有效实用的。     

Computing monodromy via continuation methods on random Riemann surfaces

We consider a Riemann surface X defined by a polynomial f(x,y) of degree d, whose coefficients are chosen randomly. Hence, we can suppose that X is smooth, that the discriminant δ(x) of f has d(d−1) simple roots, Δ, and that δ(0)≠0, i.e. the corresponding fiber has d distinct points {y₁,…,y_d}. When we lift a loop 0∈γ⊂C−Δ by a continuation method, we get d paths in X connecting {y₁,…,y_d}, hence defining a permutation of that set. This is called monodromy.Here we present experimentations in Maple to get statistics on the distribution of transpositions corresponding to loops around each point of Δ. Multiplying families of “neighbor” transpositions, we construct permutations and the subgroups of the symmetric group they generate. This allows us to establish and study experimentally two conjectures on the distribution of these transpositions and on transitivity of the generated subgroups.Assuming that these two conjectures are true, we develop tools allowing fast probabilistic algorithms for absolute multivariate polynomial factorization, under the hypothesis that the factors behave like random polynomials whose coefficients follow uniform distributions.     

连续潮流与最优潮流相结合的电力市场双侧竞价交易计划研究

电力市场双侧竟价交易中发电商和用户报价变化所导致的竟价电量波动将会引起电力系统中潮流重新分布，对安全运行产生影响。该文结合双边合同与双侧竞价并计及静态电压稳定裕度约束建立了交易模型，提出将连续潮流和最优潮流相结合，识别双方特定报价水平下网络中存在的薄弱环节，制定出既能实现社会效益最大化，又能保证系统安全运行的交易计划。IEEE30节点系统算例结果表明该文模型和方法的正确性与有效性。