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In order to improve fitting accuracy of free-form surface, an improved method for the currently recognized NURBS free-form surface based on discrete stationary wavelet transform is proposed. Firstly, the elevation image of the free-form surface point cloud and the elevation sequence of the elevation image are obtained by using the grid method. Then, feature points of the free-form surface are extracted by the discrete stationary wavelet transform. Finally, using the extracted feature points, high accuracy NURBS free-form surface is realized. Compared with the conventional NURBS method and the NURBS method based on dual-tree complex wavelet transform, the experimental results showed that the root mean squared errors of fitting results of free-form surface were deduced 77.64% and 23.16%, respectively. Therefore, the proposed method has satisfactory fitting precision.

Bidder collusion in reverse auctions is a pervasive phenomenon that leads to a series of problems for buyers and their supply chains. This work aims to conduct a hazard analysis on a first-price sealed-bid reverse auction with bidder collusion by applying colored timed Petri nets, in which places and transition nodes represent bidding resources and activities. This work successfully dissects the collusion process, quantifies the harm of collusion, and compares the harm levels. The results of the simulation disclose two main causal factors for bidder collusion information asymmetry and strong relationship between strong bidders. This study also identifies the situations where there is a strong relationship between strong bidders. Based on these findings, several recommendations are proposed to reduce the harm of the ring game in a real reverse auction process. Thus, this study helps the buyers to take control of reverse auctions.

Massive MIMO is one of the promising techniques to improve spectral efficiency and network performance for reaching its targeted multi-gigabit throughput in 5G systems. For 5G New Radio (NR) systems, one of the key differences compared to 4G systems is the utilization of high frequency millimeter wave (mmWave) bands in addition to sub-6GHz bands. To keep the complexity and implementation cost low, hybrid analog-digital beam-forming with large-scale antenna array has become a common design approach to address the issue of higher propagation loss as well as to improve spectral efficiency in mmWave communication in 5G NR. The 5G NR standard is designed to adapt to different beam-forming architecture and deployment scenarios. This paper provides the overview on beam management procedure according to the current 5G standardization progress. We discuss some major challenges of millimeter-wave communications encountered in the current 5G NR standard and present some expected enhancements considered for the future beyond-5G standard.

Bipartite consensus protocol is designed for multi-agent systems with time-varying delays. Then, the bipartite consensus problem is transformed into a corresponding stability problem by methods of gauge transformation and state transformation. The Lyapunov-Krasovskii functional is constructed, and the linear matrix inequality theory based on methods of delay partitioning and free matrix integral inequality is used to obtain sufficient conditions for a bipartite consensus of multi-agent systems. Both the first-order and second-order multi-agent systems are investigated. Finally, the effectiveness of the obtained results is illustrated by virtue of simulation results.

A kind of novel method of power allocation with limited cross-tier interference for cognitive radio network (CRN) is proposed in this paper. In this method, an interference-limited power allocation algorithm based on filter bank multi-carrier-offset quadrature amplitude modulation (FBMC-OQAM) is put forward. In order to improve the energy efficiency of the entire network and protect secondary users (SUs) in the network from too much interference, cross-tier interference limit is adopted, at the same time, virtual queue is designed to transform the extra packet delay caused by the contention for the channel of multi-user into the queuing delay. Taking the energy efficiency as the objective function, a nonlinear programming approach with nonlinear constraints is innovatively proposed under the constraints of time delay and transmission power. An iterative algorithm in order to solve the problem is also put forward. In the new algorithm, the fractional objective function is transformed into polynomial form, and the global optimal solution is obtained by iteration after reducing the computational complexity. In addition, a sub-optimal algorithm is proposed to reduce computational complexity. The experimental results show that the optimal algorithm has higher performance while the sub-optimal algorithm has a lower computational complexity. The presented method has very good practical importance for the CRN.

An auction is a crucial resource allocation mechanism for a supply chain and includes the purchasing price at the winner's bid value, eligible suppliers in winning bidder sets, and business payment terms. A multi-object auction usually involves two types of mechanisms: sequential and combinatorial auctions (CAs). A literature review reveals that the research on CAs still has some treasures waiting to be discovered. Using the framework of Petri nets, this paper employs timed and colored tokens representing every bidder's bidding data and applies transition nodes to execute bidding rules such as combinatorial discriminate analysis, bidder's bid decision-making, and the auctioneer's winner decision-making. Based on the contribution of workflows in Petri net theory, we present a case-based CA Petri net model and a sequential auction Petri net model. We compare the supply chain coordination performance of these two types of auctions and reach the conclusion under given assumptions. This paper is an attempt to apply Petri net theory to auctions and provides valuable insights for organizers to establish scientific and efficient bidding processes.