In our previous work, Fitness Predator Optimizer (FPO) is proposed to avoid premature convergence for multimodal problems. In FPO, all of the particles are seen as predators. Only the competitive, powerful predator that are selected as an elite could achieve the limited opportunity to update. The elite generation with roulette wheel selection could increase individual independence and reduce rapid social collaboration. Experimental results show that FPO is able to provide excellent performance of global exploration and local minima avoidance simultaneously. However, to the higher dimensionality of multimodal problem, the slow convergence speed becomes the bottleneck of FPO. A dynamic team model is utilized in FPO, named DFPO to accelerate the early convergence rate. In this paper, DFPO is more precisely described and its variant, DFPO-r is proposed to improve the performance of DFPO. A method of team size selection is proposed in DFPO-r to increase population diversity. The population diversity is one of the most important factors that determines the performance of the optimization algorithm. A higher degree of population diversity is able to help DFPO-r alleviate a premature convergence. The strategy of selection is to choose team size according to the higher degree of population diversity. Ten well-known multimodal benchmark functions are used to evaluate the solution capability of DFPO and DFPO-r. Six benchmark functions are extensively set to 100 dimensions to investigate the performance of DFPO and DFPO-r compared with LBest PSO, Dolphin Partner Optimization and FPO. Experimental results show that both DFPO and DFPO-r could demonstrate the desirable performance. Furthermore, DFPO-r shows better robustness performance compared with DFPO in experimental study.
Large errors of low-cost MEMS inertial measurement unit (MIMU) lead to huge navigation errors, even wrong navigation information. An integrated navigation system for unmanned vessel is proposed. It consists of a low-cost MIMU and Doppler velocity sonar (DVS). This paper presents an integrated navigation method, to improve the performance of navigation system. The integrated navigation system is tested using simulation and semi-physical simulation experiments, whose results show that attitude, velocity and position accuracy has improved awfully, giving exactly accurate navigation results. By means of the combination of low-cost MIMU and DVS, the proposed system is able to overcome fast drift problems of the low cost IMU.
A novel wool absorption board was prepared by using a traditional non-woven technique with coarse wools as the main raw material mixed with heat binding fibers. By using the transfer-function method and standing wave tube method, the sound absorption properties of wool boards in a frequency range of 250-6300 Hz were studied by changing the thickness, density, and cavity depth. Results indicated that wool boards exhibited excellent sound absorption properties, which at high frequencies were better than that at low frequencies. With increasing thickness, the sound absorption coefficients of wool boards increased at low frequencies and fluctuated at high frequencies. However, the sound absorption coefficients changed insignificantly and then improved at high frequencies with increasing density. With increasing cavity depth, the sound absorption coefficients of wool boards increased significantly at low frequencies and decreased slightly at high frequencies.
The issue of the longitudinal stability of a WIG vehicle has been a very critical design factor since the first experimental WIG vehicle has been built. A series of studies had been performed and focused on the longitudinal stability analysis. However, most studies focused on the longitudinal stability of WIG vehicle in cruise phase, and less is available on the longitudinal static stability requirement of WIG vehicle when hydrodynamics are considered: WIG vehicle usually take off from water. The present work focuses on stability requirement for longitudinal motion from taking off to landing. The model of dynamics for a WIG vehicle was developed taking into account the aerodynamic, hydrostatic and hydrodynamic forces, and then was analyzed. Following with the longitudinal static stability analysis, effect of hydrofoil was discussed. Locations of CG, aerodynamic center in pitch, aerodynamic center in height and hydrodynamic center in heave were illustrated for a stabilized WIG vehicle. The present work will further improve the longitudinal static stability theory for WIG vehicle.
The traditional clustering algorithm of Low-Energy Adaptive Clustering Hierarchy (LEACH) does not care about the residual energy of the cluster heads and the distance relationship of each node in the wireless sensor networks (WSNs). Each new round the cluster head is changed without any concern about the residual energy of the current cluster head, and the nodes join into a new cluster head without concern about the distance factor and the residual energy factor of all nodes in WSNs. To solve these problems in LEACH, this paper puts forward a distributed energy balance clustering algorithm, which takes into full consideration the residual energy of the cluster heads and the distance relationship between the base station and the cluster heads. The experimental results indicate that the proposed distributed energy balance clustering algorithm can prolong the lifetime of the networks more than LEACH, and the number of messages for selecting a new cluster head at the same time can be greatly reduced, which proves it as more suitable for practical applications.
HPV is classified into high-risk and low-risk types depending on its probability of leading to tumorigenesis. Many studies have shown that HPV infection, especially the infection caused by the high-risk type, is always related to prostate cancer, bladder cancer, penile cancer, testicular cancer, and other urinary system tumors. However, previous studies differed in sexual openness and racial genetic susceptibility of the study object, sample size, and experimental methods. Hence, the correlation between high-risk HPV infection and urinary system tumors remains controversial. The early open reading frame of the HPV genome is composed of E1–E7, among which E6 and E7 are the key transfer proteins. The combination of these proteins with oncogene and anti-oncogene may be one of the mechanisms leading to tumorigenesis.
Radical hysterectomy (RH) and pelvic lymphadenectomy are the main treatment methods for early cervical cancer and endometrial carcinoma. Effective care measures, however, can decrease the incidence of UTIs and complications associated with RH and pelvic lymphadenectomy, as well as improve the therapeutic effects of administered drugs and patient prognosis. The writer refers to relevant literatures to analyze the reasons for postoperative UTIs and to provide a brief summary of the nursing methods for and progress in UTI prevention.
This paper discusses the firm-level determinants of international hotels’ foreign markets entry choices, contrasting acquisition with management and franchise contracts, based on a resource-dependency perspective and appropriability theory. It points out that brand equity, relatedness of products and market segmentation, partner-specific knowledge of hotels, international experience, and the duration of proprietary knowledge impact hotels’ decisions on how to enter a foreign market. In addition, the paper suggests the existence of entry choices sequence favorable to acquisition probability after the end of management contract when the franchisors’ or management companies’ proprietary knowledge attenuates. Contract activity is likely to be renewed after the acquisition, once the management company has established a new form or a higher level of proprietary knowledge.