A chaotic spread spectrum system for underwater acoustic communication

The work is supported in part by NSFC (Grant no. 61172070), IRT of Shaanxi Province (2013KCT-04), EPSRC (Grant no.Ep/1032606/1).Peer reviewedPostprin

Thought on Giving up Farming and Returning the Wood (grass): taking the passage west of the Yellow River as an example

As the transitional part between oasis and desert, giving up farming and returning the wood (grass) in the edge of the desert can prevent sand dune effectively and from becoming desert of the oasis so as to protect ecosystem. However, the problems that the original plants will be damaged due to the unreasonability in choosing species or the new plants will die due to mismanagement must be solved because the environment of the edge of the desert is very special. Otherwise, they will bring about some negative effect. This paper puts forward my own understanding and thought on these problems. Key words: desert, edge, giving up farming and returning the wood (grass), thought Résumé : La région marginale du désert est un secteur de passage entre l’oasis et le désert , la mise en application du retour de la culture au reboisement est une mesure très efficace pour empêcher le mouvement de la dune , la désertification de l’écologie de l’oasis et pour protéger l’environnement écologique , mais vu les particularités de l’environnement dans la région marginale du désert , l’ écologie sera atteinte si les problèmes des choix inconvenables des espèces dans ce processus , l’imperfectionnement de la gestion, ne sont pas résolus sans retarder Mots-clés : désert , région marginale , retour de la culture au reboisement , réflexion 摘要：沙漠邊緣地帶作為綠洲與沙漠的過度地段，實施退耕還林（草）可以有效的防止沙丘的移動，阻止綠洲生態的進一步沙漠化，保護生態環境，但是沙漠邊緣地帶因其環境的特殊性，在退耕還林（草）中由於物種選擇不合理、原生植被被破壞、管理不善導致初生植被死亡等問題，若不及時解決，則會給生態帶來一定的負面效應。本文針對這一問題提出自己的認識與思考。 關鍵詞：沙漠；邊緣地帶；退耕還林（草）；思

A rapid staining-assisted wood sampling method for PCR-based detection of pine wood nematode Bursaphelenchus xylophilus in Pinus massoniana wood tissue

For reasons of unequal distribution of more than one nematode species in wood, and limited availability of wood samples required for the PCR-based method for detecting pinewood nematodes in wood tissue of Pinus massoniana, a rapid staining-assisted wood sampling method aiding PCR-based detection of the pine wood nematode Bursaphelenchus xylophilus (Bx) in small wood samples of P. massoniana was developed in this study. This comprised a series of new techniques: sampling, mass estimations of nematodes using staining techniques, and lowest limit Bx nematode mass determination for PCR detection. The procedure was undertaken on three adjoining 5-mg wood cross-sections, of 0.5 · 0.5 · 0.015 cm dimension, that were cut from a wood sample of 0.5 · 0.5 · 0.5 cm initially, then the larger wood sample was stained by acid fuchsin, from which two 5-mg wood cross-sections (that adjoined the three 5-mg wood cross-sections, mentioned above) were cut. Nematode-staining-spots (NSSs) in each of the two stained sections were counted under a microscope at 100· magnification. If there were eight or more NSSs present, the adjoining three sections were used for PCR assays. The B. xylophilus – specific amplicon of 403 bp (DQ855275) was generated by PCR assay from 100.00% of 5-mg wood cross-sections that contained more than eight Bx NSSs by the PCR assay. The entire sampling procedure took only 10 min indicating that it is suitable for the fast estimation of nematode numbers in the wood of P. massonina as the prelimary sample selections for other more expensive Bx-detection methods such as PCR assay

The Finite Element Analysis of the Deflection of the Crankshaft of Rotary Compressor

The deflection of the crankshaft which transfers the power of motor to the pump of the compressor directly affects the vibration, noises and wear problems in the rotary compressor, therefore, with the requirement of higher reliability, it is important to obtain it exactly in compressor design. Various forces that the crankshaft suffers were calculated by theoretical analysis in the operation process of the compressor. And based on the finite element method (FEM), the deflection of the crankshaft was obtained by simulation in the rotary compressor. And then the measurements were performed concerning the orbit of the top dead centre of the crankshaft with non-contacting displacement sensors in the compressor. In comparison with the tests, the validity of the calculation method was verified. It was found that the results of calculation were good agreement with the tests’. In addition, several factors which affect the deflection of the crankshaft were analyzed with the FEM, and the influences of flange height, shaft diameter, mechanical air gap in the motor, rotor weight on the deflection were found distinctly, which as a primary theoretical basis is provided for the compressor design

Rock-Cutting Performance Experimental Research of Particle Water Jet Based on Orthogonal Experimental Method

Particle Impact Drilling is an efficient drilling technology for deep-well hard formation which cuts rock mainly by high-speed spherical particle impacting rock with the help of hydraulic action and mechanical action. In order to determine main influence factors and their order of priority, the orthogonal experiment was designed and the experimental data was analyzed with both the general method and the variance method. The analysis indicates that the order of priority of the main influence factors of particle water jet rock-cutting performance is pump pressure ps, impacting range S, particle mass concentration ω, confining pressure P and particle diameter dp. Moreover, ps is highly important and S and ω are important. In addition, high ps, moderate S, moderate ω, moderate dp and low P could effectively promote particle water jet to impact and cut rocks. Key words: Deep hard formation; Particle impact drilling; Particle water jet; Rock-cutting performance; Orthogonal experiment method; Analysis of varianc

OVERRIDING CISPLATIN RESISTANCE IN LUNG SQUAMOUS CELL CARCINOMA: INSIGHTS FROM COMBINATION WITH HDAC INHIBITOR

Ph.DDOCTOR OF PHILOSOPH