Plant Age Effect on Mechanical Properties of Moso Bamboo (Phyllostachys Heterocycla Var. Pubescens) Single Fibers

Bamboo fiber has greater mechanical strength than certain other natural fibers and could therefore be a candidate for production of fiber-reinforced composites. Single fibers were isolated from Moso bamboo samples taken from plants between 0.5 and 8.5 yr old. Mechanical properties of single fibers (tensile strength, modulus of elasticity (MOE), and other mechanical related properties such as the microfibril angle and fiber cross-sectional area) were studied. There was no significant variation with age in average MOE and fracture strain of the bamboo fibers. Results indicate that the thickening growth of cell walls in bamboo fibers near the outer surface of bamboo is almost complete by 0.5 yr. Therefore, fibers from 0.5 to 8.5 yr old plants may be used for making fiber-reinforced composites

Using optimized random amplified polymorphic DNA (RAPD) markers to identify the category status of Citrus nobilis Lour. Gonggan

Citrus nobilis Lour. Gonggan is an excellent fruit variety which is widely planted in South China. The origin of Gonggan is not clear. It is conjectured that its origin is from a cross between tangerine and orange; however, there is no direct evidence to confirm this. Here, we applied the optimized random amplified polymorphic DNA (RAPD)-PCR to amplify genus Citrus species: 1) to better understand the genetic relationship between C. nobilis Lour. Gonggan and other Citrus species; and (2) to address the phylogenetic relationship among Citrus species. A total of 21 RAPD primers were used to screen 4 Citrus species and 10 of them efficiently amplified the genomic DNA of 23 Citrus accessions. A total of 87 locus/alleles were generated by those 10 primers with an average of 97.7% polymorphic. Our data supported that C. nobilis Lour. Gonggan belongs to a big group with most tested tangerine and orange and a subgroup with Citrus haniana and Citrus flamea, implying that either C. haniana or C. flamea is likely to be one of the parents of C. nobilis Lour. Gonggan.Key words: Citrus nobilis Lour. Gonggan, random amplified polymorphism DNA (RAPD), phylogeneticrelationshi

Dual Control of Exploration and Exploitation for Auto-Optimisation Control with Active Learning

The quest for optimal operation in environments with unknowns and uncertainties is highly desirable but critically challenging across numerous fields. This paper develops a dual control framework for exploration and exploitation (DCEE) to solve an auto-optimisation problem in such complex settings. In general, there is a fundamental conflict between tracking an unknown optimal operational condition and parameter identification. The DCEE framework stands out by eliminating the need for additional perturbation signals, a common requirement in existing adaptive control methods. Instead, it inherently incorporates an exploration mechanism, actively probing the uncertain environment to diminish belief uncertainty. An ensemble based multi-estimator approach is developed to learn the environmental parameters and in the meanwhile quantify the estimation uncertainty in real time. The control action is devised with dual effects, which not only minimises the tracking error between the current state and the believed unknown optimal operational condition but also reduces belief uncertainty by proactively exploring the environment. Formal properties of the proposed DCEE framework like convergence are established. A numerical example is used to validate the effectiveness of the proposed DCEE. Simulation results for maximum power point tracking are provided to further demonstrate the potential of this new framework in real world applications

A new impedance matching method for an ultra-wide band and dual circularly polarised feed

In traditional antenna design, metal components are not placed in the central part of the antenna as they change the characteristics of near field radiation. However, we show that placing a metal ring in the centre of the strip lines, which connect the ends of folded high-frequency dipoles, does not damage the performance of the feed. Instead it significantly improves the voltage standing wave ratio of the feed whilst other performance indicators are not compromised. Thus, our findings show an excellent way of improving the wide band feed. Based on this foundation, a new circularly polarised feed for operation between 0.4 to 2 GHz is introduced for the Chinese Spectral Radioheliograph in this paper. The issue of a feed impedance matching network is investigated. By optimising the impedance matching, the performance of the feed is enhanced with respect to the previous realisations of the Eleven feed. The simulation and experimental results show that the gain of the feed is about 10 dBi, and the VSWR is less than 2:1. In addition, the feed has a low axial ratio, fixed phase centre location, and constant beam width in the range of 0.4 to 2 GHz

Research on Automatic Identification of Rumors in Stock Forum Based on Machine Learning

When rumors prevail in securities market, it is very difficult for investors to identify valid information. In the meantime, investors have much more ways to access information with the evolution of internet. But there is an overwhelming quantity of information on the Internet, the coexistence of facts and rumors, namely, “widely circulated” and “specious”, yet “unconfirmed officially” vague information, makes it more difficult for investors who with limited rationality to distinguish facts from rumors. Existing studies are mainly devoted in the method of event study, namely screening rumors from “official channels” that clarified, which is neither timely efficient in terms of accessing to rumors nor providing the basis for decision-making. Traditional news has evolved into various forms of social media, including forums, blogs, micro-blogs etc., and users can not only gain quick access to more valuable and timely information, but also amplify information that embed the news effectively by participating in commenting on various social media. Dynamic information creation, sharing and coordination among Web users are exerting increasingly prominent impact on the securities market in now days. Thus, it is very necessary to study the effects of social media as online forums on the securities market. In this paper, the method of machine learning is adopted for the first time to identifying the Internet rumors automatically, and successfully in crawling massive forum data by smart computer technology. Unlike the case study and statistical sampling of rumors, this paper conduct automatic identification of Internet rumors by utilize the smart technology, thus paving the way for more in-depth analysis about the effects of Internet media on the securities market in future

A study of instability in a miniature flying-wing aircraft in high-speed taxi

AbstractThis study investigates an instability that was observed during high-speed taxi tests of an experimental flying-wing aircraft. In order to resolve the reason of instability and probable solution of it, the instability was reproduced in simulations. An analysis revealed the unique stability characteristics of this aircraft. This aircraft has a rigid connection between the nose wheel steering mechanism and an electric servo, which is different from aircraft with a conventional tricycle landing gear system. The analysis based on simulation results suggests that there are two reasons for the instability. The first reason is a reversal of the lateral velocity of the nose wheel. The second reason is that the moment about the center of gravity created by the lateral friction force from the nose wheel is larger than that from the lateral friction force from the main wheels. These problems were corrected by changing the ground pitch angle. Simulations show that reducing the ground pitch angle can eliminate the instability in high-speed taxi

(S)-Ethyl 2-[4-(6-chloro­quinoxalin-2-yl­oxy)phen­oxy]propanoate

In the mol­ecule of the title compound, C19H17ClN2O4, the quinoxaline ring system is planar [maximum deviation = 0.013 (3) Å] and oriented at a dihedral angle of 80.18 (3)° with respect to the benzene ring. In the crystal structure, inter­molecular C—H⋯N inter­actions link mol­ecules into chains. π–π contacts between the quinoxaline systems [centroid–centroid distance = 3.654 (1) Å] may further stabilize the structure