水稻植质钵盘高强度结构设计与性能试验

针对水稻植质钵盘应用过程中存在的问题，对水稻植质钵盘结构进行改进设计。阐述水稻植质钵盘设计思想，探讨水稻植质钵盘结构改进设计思路及结构设计依据，分析改进前后的水稻植质钵盘结构强度，同时分别以改进前的水稻植质钵盘（CKl）、日本塑料钵盘（CK2）和平育秧盘（CK3）为水稻育秧载体，通过多年田间对比试验探讨改进后的水稻植质钵盘（CK）对水稻生产的影响。试验结果表明：改进后的水稻植质钵盘正应力较改进前水稻植质钵盘提高15．09％；CK和CKl秧苗移栽后均无缓苗期，CK2和CK3秧苗均需一定缓苗期；在生育期和收获期，CK和CKl秧苗素质均无显著差异，但均优于CK2和CK3秧苗素质；CK生产投入均低于CKl和CK2生产投入，但高于CK3生产投入；CK和CKl土壤有机质含量相同，在0～10cm、10～20cm和20—30cm土层，CK土壤有机质含量分别较CK2和CK3土壤有机质含量提高7．06％、10．08％，2．53％、3．34％，0．48％、0．11％；CK和CKl对土壤容重影响程度相同，与CK2和CK3相比较，在相同土层，CK能够促使土壤容重减小；CK和CKl产量持平，较CK2和CK3，产量分别提高10．59％和13．54％。

飞机HIRF防护设计与验证技术综述

高强度辐射场(HIRF)防护作为飞机研制的新要求,在我国起步晚,与国外差距较大。介绍了国内外飞机HIRF防护设计要求和验证技术的发展现状,简述了飞机HIRF防护设计需求,综述了民用飞机HIRF符合性验证流程,介绍并分析了当前国外主流的HIRF试验方法。并针对我国HIRF发展的迫切需求,对我国HIRF防护研究发展方向进行了分析并给出了相应的建议。

Failure mechanism of bolting support and high-strength bolt-grouting technology for deep and soft surrounding rock with high stress

In deep underground mining, the surrounding rocks are very soft with high stress. Their deformation and destruction are serious, and frequent failures occur on the bolt support. The failure mechanism of bolt support is proposed to solve these problems. A calculation theory is established on the bond strength of the interface between the anchoring agent and surrounding rocks. An analysis is made on the influence law of different mechanical parameters of surrounding rocks on the interfacial bond strength. Based on the research, a new high-strength bolt-grouting technology is developed and applied on site. Besides, some helpful engineering suggestions and measures are proposed. The research shows that the serious deformation and failure, and the lower bond strength are the major factors causing frequent failures of bolt support. So, the bolt could not give full play to its supporting potential. It is also shown that as the integrity, strength, interface dilatancy and stress of surrounding rocks are improved, the bond strength will increase. So, the anchoring force on surrounding rocks can be effectively improved by employing an anchoring agent with high sand content, mechanical anchoring means, or grouting reinforcement. The new technology has advantages in a high strength, imposing pre-tightening force, and giving full play to the bolt supporting potential. Hence, it can improve the control effect on surrounding rocks. All these could be helpful references for the design of bolt support in deep underground mines.

The construction design and practice of Three Gorges Project

The construction of Three Gorges Project (TGP) is characterized by large construction scale,high construction intensity and complexity in technology.In view of various technical difficulties such as navigation in construction period,two river closures,high-intensity concrete and earth-rock construction,high-intensity construction and demolition of RCC (roller compacted concrete) cofferdam in stage III and immediate navigation of double-line five-step shiplock after impoundment of reservoir,the scheme of river diversion during construction is adopted,namely "diversion in 3 stages,open channel navigation and cofferdam power generation".The practice and innovation achievements in river diversion during construction as well as earth-rock and concrete construction are presented emphatically.

Influence of solar wind dynamic pressure on geomagnetic Dst index during various magnetic storms

The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current.However,all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity.In this paper,based on the Burton's equations and employing two independent methods,we will show a positive correlation between pressure-correction coefficient b and the intensity of the storms.We divided our storm database(872 storms in total) into three categories according to the intensity of storms.In order to improve the accuracy of calculating,we also used the higher-resolution SYM-H index data instead of Dst index to compute the corrected Dst index during different storms.Furthermore,we are able to provide corrected magnetic storm index with high-time resolution(-1 min).

A novel microstructural design and heat treatment technique based on gradient control of carbon partitioning between austenite and martensite for high strength steels

Based on gradient control of carbon partitioning between martensite and austenite during heat treatment of steels,a stepping-quenching-partitioning(S-Q-P) process is developed for high strength steels.The S-Q-P process involves several quenching processes at progressively lower temperatures between martensite-start(Ms) and martensite-finish(Mf) temperatures,each followed by a partitioning treatment at either the initial quenching temperature or above that temperature.A novel microstructure is designed based on the S-Q-P process.Sizes and distributions of retained austenite and high-carbon martensite surrounded by martensite laths can be manipulated by the partitioning duration and temperature,and quenching temperature of the S-Q-P process.Alloying element Si is employed in the S-Q-P steel to suppress formation of carbides and create suitable amount of retained austenite.A steel of 0.39C-1.22Mn-1.12Si-0.23Cr(wt.%) treated by the S-Q-P process is endowed with some special microstructural characteristics:some strips of retained austenite located at edges of martensite blocks with high density of dislocations and between martensite laths,some small blocks of twinned martensites distributed among bundles of the low-carbon martensite lath.The mechanical properties of the medium carbon steel after the S-Q-P process can reach ultimate tensile strength(Rm) of 1240 MPa,total elongation(EI) of 25%,and product of strength and ductility(PSD) of 31.2 GPa% that are much more improved than those after the conventional quenching-tempering(Q-T) and currently prevailing quenching-partitioning(Q-P) treatments.The PSD of the tested steel after the S-Q-P process increases by 67% and 32% as compared with those after the Q-T and Q-P processes,respectively.

Prototype of a large neutron detector based on MWPC

A prototype of large-area position sensitive neutron detector was designed and constructed according to the requirements of the Small-Angle Scattering spectrometer of China Spallation Neutron Source(CSNS).The detector was based on the 3He neutron convertor and MWPC with an effective area of 650 mm×650 mm.A prototype was completed and tested with 55Fe X-ray.The high-pressure vessel was designed and constructed with high-strength aluminum alloy.A position resolution of about 4.6mm×2.3 mm(FWHM)and efficiency>65%for neutrons with wavelength of 1.8?was determined after the operational gas filled.