Development of Forming Method of Deployable Boom from Thermoplastic Polymer Composite

This paper studies deployable elements which are used in satellites and different terrestrial antenna devices. Many deployable elements are made from steel or thermoset polymer composite materials and have the following disadvantages like length limitation of deployable elements, labour intensity of manufacturing process of deployable elements etc. For this purpose a deployable tube boom element was chosen and a forming method for manufacturing deployable tube element from thermoplastic polymer composite material was developed.

A Discrete Hidden Markov Model for SMS Spam Detection

Many machine learning methods have been applied for short messaging service (SMS) spam detection, including traditional methods such as naïve Bayes (NB), vector space model (VSM), and support vector machine (SVM), and novel methods such as long short-term memory (LSTM) and the convolutional neural network (CNN). These methods are based on the well-known bag of words (BoW) model, which assumes documents are unordered collection of words. This assumption overlooks an important piece of information, i.e., word order. Moreover, the term frequency, which counts the number of occurrences of each word in SMS, is unable to distinguish the importance of words, due to the length limitation of SMS. This paper proposes a new method based on the discrete hidden Markov model (HMM) to use the word order information and to solve the low term frequency issue in SMS spam detection. The popularly adopted SMS spam dataset from the UCI machine learning repository is used for performance analysis of the proposed HMM method. The overall performance is compatible with deep learning by employing CNN and LSTM models. A Chinese SMS spam dataset with 2000 messages is used for further performance evaluation. Experiments show that the proposed HMM method is not language-sensitive and can identify spam with high accuracy on both datasets.

Numberical Simulation of Labyrinth Screw Pump with Separated Structure by Fluent

3D model and grid was conducted in Gambit,while single-phase flow field in the pump was simulated in CFD code-Fluent,by means of multiple reference frame (MRF) method, Renormalization group k-ε two-equation turbulence model (RNG k-εmodel) and Semi-Implicit Method for Pressure-Linked Equations (SIMPLEC) algorithm. Aim at problems generated by pump body such as body length limitation on pressure increasing, three new structure of labyrinth screw pumps,rotor separated LSP,stator separated LSP and rotor stator all separated LSP, were put forward in this paper.The analytical results got by contrasted pump hydraulic performance of different structure models indicated that pressure increasing magnitude and pressure increasing rate of the three separated pumps is larger compared to the unseparated pumps,and the conclusion was achieved that pump performance can be optimized through separating rotor or stator into sections by making ring slots on screw body.

An anomaly against a current paradigm – extremely low rates of individual fecundity variability of the Gordian worm (Nematomorpha: Gordiida)

SUMMARYExtreme variation in reproductive success (VRS) has been reported as a common feature of populations. Few individuals producing most of the offspring for the next generation has potential consequences for the population dynamics, genetics, and evolution of a group of organisms. High VRS has been described as a normal feature of helminth populations, although studies have focused largely on parasites of vertebrate hosts. Paragordius varius, a parasite of crickets, was used as a model system to study VRS. In this life cycle, worms absorb and store resources for reproduction from their hosts before being released into water. Egg output varied significantly with worm length, indicating that female length is an excellent predictor of fecundity. Analyses using the Lorenz curve and Gini coefficient suggest that there were no marked fecundity differences. This result was supported by data collected from a natural gordiid population, Gordius difficilis, suggesting that within gordiid populations the offspring of the next generation are contributed nearly equally by females. In addition, male body length appeared to be limited by intensity, whereas females showed no length limitation by crowding. These results contrast previous studies of parasites.