Inversion of Stress Fields in the Middle Section of the Xiaojiang Fault and Its Adjacent Area

With waveform data of 613 earthquakes with ML ≥ 2. 5 in the middle section of the Xiaojiang fault and its adjacent area which occurred during January,1998 to September 2007,focal mechanisms were calculated by the direct wave amplitude ratio of S /P in the vertical component and their characteristics were analyzed. According to regional tectonic features of the middle section of the Xiaojiang fault and its adjacent area,the study region was partitioned into two zones with the Xiaojiang fault as the boundary,e. g. zone A and zone B (including the Xiaojiang fault). In order to research the faults stress in detail,the Xiaojiang fault zone was picked out for independent analysis. The study region was also partitioned into 1°× 1° cells with a 0. 5° step. The stress fields of zone A,B and the fault zone were inverted with the FMSI method (Gephart,1990). The results show that first, the faults are mainly of strike-slip in the middle section and its adjacent area,amounting to 81. 28%,69. 23% and 72. 97% in the A,B and fault zones,respectively. Secondly,the stress inversion also indicates that the directions of maximum principal stress σ1 in the A, B,and fault zones are approximately NNW,NWW and NWW,the stress action is mainly horizontal,and strike-slip faulting is dominant in the study area. On the other hand,the direction of the principal stress field in the central Yunnan block changed from NNW to NWW,however,in the region between the Yuanmou and Pudu River faults,the azimuth of the main compressive stress shows that the north-south slip is obvious. While the direction of the main compressive stress of the Xiaojiang fault zone is nearly NW; in the east of the Xiaojiang fault,the direction of principal compressive stress is NW to NNW in the eastern Yunnan block.

Chemical Weeding in Dry Direct Seeding Fields of Single Cropping Middlelate Rice

Chemical weeding in dry direct seeding fields of single cropping middle-late rice was studied in Huida vegetable farm of Huizhou City in 2012. The main treatment was herbicide（ pretilachlor ＋ bensulfuron-methyl,Yangguo and butachlor）,and the sub-treatment was application method（ soil treatments,seedling treatment and integrated treatment）. The results showed that 80 g pretilachlor ＋ bensulfuron-methyl（ 36% pretilachlor ＋ 4% bensulfuron-methyl） diluted with 50 kg water could be sprayed or 200 g Yangguo（ 23. 9% butachlor ＋ 1. 1% bensulfuron-methyl） mixed with 15 kg sandy soil could be broadcasted per 667 m2 on the sowing day or the second day under moist condition of soil,which could effectively control weeds in dry direct seeding fields of single cropping middle-late rice.

Effect of Middle-frequency Electromagnetic Field on the Semi-continuous Casting for ZK60 Billets

The semi-continuous casting of ZK60 magnesium alloy under different middle frequency electromagnetic field conditions was examined.Effects of middle frequency electromagnetic field on microstructure,precipitations and tensile properties are investigated.The results show that the microstructures of ZK60 magnesium alloy are refined and distribution uniformity of precipitations is observed after applying the middle frequency electromagnetic field.And the tensile properties of the billets produced by middle frequency electromagnetic field are increased.

Field Efficacy Trial and Optimum Control Period of Rice False Smut(Ustilaginoidea virens) in Single Cropping Middle-late Rice

[Objective]The paper was to study optimum chemical agents and control periods against rice false smut( Ustilaginoidea virens) in single cropping middle-late rice. [Method]Taking chemical agents( triadimefon,armure,Jinggangmycin) as main treatments and spraying periods( within 7 d before initial heading stage,within 7 d before initial heading stage + initial heading stage,initial heading stage) as assisted treatments,the field efficacy trial and optimum control period of U. virens in single cropping middle-late rice were studied using Huanghuazhan and Jinnongsimiao as experimental materials in 2013. [Result] Three chemical agents,triadimefon,armure,Jinggangmycin,extremely reduced diseased panicle rate and disease index of U. virens,but there was no significant difference among three chemical agents. Spraying period did not have significant impact on diseased panicle rate and disease index of U. virens,whereas spraying within7 d before initial heading stage and during initial heading stage had relatively good control effect. Yield increased significantly after application of three chemical agents,and armure led to greater increase. The reason for yield increase was that seed setting rate was significantly increased,and the number of filled grains per panicle was significantly increased. Although spraying period influenced yield,the difference was not significant. [Conclusion] Triadimefon,armure and Jinggangmycin had good control effects against U. virens in single cropping middle-late rice,of which armure had better control effects. Spraying chemical agents increased seed setting rate,and further increased the number of filled grains per panicle and yield. Spraying within 7 d before initial heading stage and during initial heading stage had relatively better control effect against U. virens.

Influence of a drain field plate on the forward blocking characteristics of an AlGaN/GaN high electron mobility transistor

In this paper, the influence of a drain field plate （FP） on the forward blocking characteristics of an AlGaN/GaN high electron mobility transistor （HEMT） is investigated. The HEMT with only a gate FP is optimized, and breakdown voltage VBR is saturated at 1085 V for gate–drain spacing LGD ≥ 8 μm. On the basis of the HEMT with a gate FP, a drain FP is added with LGD=10 μm. For the length of the drain FP LDF ≤ 2 μm, VBR is almost kept at 1085 V, showing no degradation. When LDF exceeds 2 μm, VBR decreases obviously as LDF increases. Moreover, the larger the LDF, the larger the decrease of VBR. It is concluded that the distance between the gate edge and the drain FP edge should be larger than a certain value to prevent the drain FP from affecting the forward blocking voltage and the value should be equal to the LGD at which VBR begins to saturate in the first structure. The electric field and potential distribution are simulated and analyzed to account for the decrease of VBR.

Forward modeling for “earth-ionosphere” mode electromagnetic field

A fixed artificial source(greater than 200 kW) was used and the source location was selected at a high resistivity region to ensure high emission efficiency. Some publications used the "earth-ionosphere" mode in modeling the electromagnetic(EM) fields with the offset up to a thousand kilometer, and such EM fields still have a signal/noise ratio of 10-20 dB. This means that a new EM method with fixed source is feasible, but in their calculation, the displacement in air was neglected. In this work, some three-layer modeling results were presented to illustrate the basic EM fields' characteristics in the near, far and waveguide areas under "earth-ionosphere" mode, and a standard is given to distinguish the boundary of near, far and waveguide areas. Due to the influence of the ionosphere and displacement current in the air, the "earth-ionosphere" mode EM fields have an extra waveguide zone, where the fields' behavior is very different from that of the far field zone.

Positive carbon isotope excursions:global correlation and genesis in the Middle-Upper Ordovician in the northern Tarim Basin,Northwest China

Stable carbon isotope ratio （δ13Ccarb） analysis has been widely applied to the study of the inter-conti- nental or global marine carbonate correlation. Large-scale Cambrian-Ordovician carbonate platforms were developed in the Tarim Basin. But research on fluctuation character- istics and global correlation of δ13Ccarb is still weak. Based on conodont biostratigraphy and whole-rock δ13Ccarb data in the Tahe oil-gas field of the northern Tarim Basin, the global correlation and genesis of positive carbon isotope excursions in the Darriwilian--Early Katian was exam- ined. Three positive excursions were identified in the Tahe oil-gas field including the middle Darriwilian carbon iso- tope excursion （MDICE）, the Guttenberg carbon isotope excursion （GICE）, and a positive excursion within the Pygodus anserinus conodont zone which is named the Early Sandbian carbon isotope excursion （ESICE） in this paper. Furthermore, these positive excursions had no direct relation with sea level fluctuations. MDICE and GICE could be globally correlated. The Middle-Upper Ordovi- cian Saergan Formation source rocks of the Kalpin outcrops were in accordance with the geological time of MDICE and ESICE. GICE had close relationship with the source rock of the Lianglitag Formation in the basin.Massive organic carbon burial was an important factor controlling the genesis of these positive excursions.

A Mean-Field Stochastic Maximum Principle for Optimal Control of Forward-Backward Stochastic Differential Equations with Jumps via Malliavin Calculus

This paper considers a mean-field type stochastic control problem where the dynamics is governed by a forward and backward stochastic differential equation (SDE) driven by Lévy processes and the information available to the controller is possibly less than the overall information. All the system coefficients and the objective performance functional are allowed to be random, possibly non-Markovian. Malliavin calculus is employed to derive a maximum principle for the optimal control of such a system where the adjoint process is explicitly expressed.

基于变前视距离的四轮同步转向农机改进纯跟踪控制

路径跟踪控制是提高自主导航系统控制精度的关键。针对在复杂农田作业环境下转弯时纯跟踪算法跟踪精度不高的问题,本文提出了一种基于改进纯追踪模型的四轮同步转向农机路径跟踪控制算法。建立了基于四轮同步转向农机的运动学模型和纯跟踪模型,在此基础上考虑航向误差得到改进纯跟踪模型,进行RTK定位坐标修正,根据量化误差的评价函数搜索前视区域最优目标点,得到最优前视距离。本文算法能实时确定四轮同步转向农机改进纯跟踪模型中的前视距离,使航向误差和横向误差最小化,实现目标点的自适应优化。仿真结果表明,本文方法转弯时平均绝对横向误差减至0.035 m,平均绝对航向误差减至0.212°;水田实验结果表明,当四轮同步转向农机作业速度为3.6 km/h时,四轮转向农机轨迹跟踪平均绝对横向误差减至0.109 m,平均绝对航向误差减至2.799°,转弯跟踪精度显著提高。

全波形发射电流激发下地面瞬变电磁法磁场特征

在过去四十年,大部分关于瞬变电磁法的三维建模和反演研究都聚焦于磁场时间导数,而对于磁场数据研究并不多见.如今,随着超导量子干涉仪(SQUID)技术日益成熟,基于磁场数据的瞬变电磁法探测案例逐渐增多.基于矢量有限单元法,采用频谱法和时步法分别实现了适用于瞬变电磁法磁场数据的三维正演.以低阻覆盖层下的良导体和均匀半空间中板状良导体模型为例,研究了全波形发射电流激发的瞬变电磁法磁场及其时间导数特征,并探讨了二者对深部良导体的探测能力.正演计算结果表明:由于受发射电流全波形效应影响,晚延时磁场随目标体电导率增大而先增强、后减弱,然而即使不考虑全波形效应,磁场时间导数也呈现上述规律;在高阻和低阻围岩情形中,磁场比其时间导数对深部良导体反映更加灵敏,并且晚延时磁场比其时间导数更不易受地磁场背景噪声干扰,说明磁场比其时间导数更适合于深部良导体探测.需要注意的是,发射电流全波形效应降低了瞬变电磁法对深部良导体的识别能力,建议在瞬变电磁法对块状或脉状金属硫化物矿床探测时,尽量采用低基频发射电流波形.

“双高计划”背景下构建现场工程师产业学院研究

成立现场工程师产业学院是响应产教深度融合,促进“双高计划”建设的重要举措。目前,现场工程师产业学院建设仍然存在人才定位不够清晰、主体责任不够明确、师资队伍有待加强等问题,可从构建“政院企校”四位一体协同育人机制、探索“四阶”一体化贯通人才培养路径、打造高水平结构化双师教学团队、构建产业学院“校中厂”和“厂中校”、创新现场工程师人才评价机制等方面开展实践探索,为现场工程师产业学院建设加大助力,实现“双高计划”建设“加速度”。

准噶尔盆地克拉美丽气田及周缘天然气成因来源再认识与勘探启示

克拉美丽气田石炭系气藏已探明天然气地质储量832.4×10^(8) m^(3),是准噶尔盆地已发现的最大天然气田。为了进一步探索、评价、深化对克拉美丽气田及其周缘天然气气源潜力认识,推动发现新气田,对5套地层、38口井、65个天然气样品进行分析,并基于天然气组分和天然气稳定碳同位素组成,系统研究了其成因、来源和遭受的次生改造作用,提出了新的天然气勘探领域。研究结果表明:(1)克拉美丽气田及其周缘存在4种不同成因来源的天然气,第Ⅰ类和第Ⅱ类天然气为煤成气,第Ⅲ类天然气为浅埋藏期伴生原油发生生物降解形成的次生生物成因气(混合热成因气),第Ⅳ类天然气为油型气;(2)部分天然气样品Δδ^(13)C(C_(3)—C_(2))和i-C_(4)/n-C_(4)值异常增加,其重烃气组分遭受了细菌的选择性降解;(3)石炭系滴水泉组烃源岩较巴塔玛依内山组烃源岩分布更广,连续性更好,规模更大,二叠系平地泉组烃源岩在盆地南部已普遍达到高成熟—过成熟阶段,滴水泉组和平地泉组2套烃源岩形成的含油气系统有望成为盆地深层—超深层天然气规模勘探的新领域;(4)次生生物成因气埋藏浅,甲烷浓度高,开采成本低,建产快,且在准噶尔盆地广泛分布,是浅层天然气高效勘探的重要领域。结论认为,天然气成因来源的再认识深化了准噶尔盆地克拉美丽气田及其周缘天然气资源的认识,揭示了盆地深层—超深层和浅层天然气是天然气勘探战略接替领域,对推动盆地实现以石油勘探为主向“油气并举”的重大转变提供了重要技术参考。

基于复变函数理论的无中导连拱隧道应力与位移解析解

无中导连拱隧道由于后行洞衬砌搭接于先行洞衬砌拱腰之上,围岩与衬砌受力情况复杂,开展相应的围岩与衬砌应力和位移分析具有重要的工程意义。基于复变函数理论和Schwarz交替法,提出了深埋条件下考虑衬砌的无中导连拱隧道围岩与衬砌应力和变形的计算方法。针对无中导连拱隧道两洞具有共用边界的特点,在利用柯西积分法进行求解时,将单洞衬砌与围岩接触的边界积分条件转化为仅存在单洞时的完整边界积分与共用边界积分之差,对于Schwarz交替法中求解“附加面力”的过程亦进行类似处理。给出共用边界应力与位移的计算方法。通过算例,将上述解析结果和数值仿真结果进行对比,证明了方法的可行性和准确性。

水下中远场爆炸冲击波作用下航行体表面动态响应分析

针对水下中远场爆炸作用下航行体表面动态响应复杂、预测困难的问题,基于任意欧拉-拉格朗日数值算法,考虑自由面对冲击波反射的影响,利用爆炸相似理论细化模型网格,运用有限元软件对水下爆炸模型进行求解。分析冲击波作用下航行体表面动态应力峰值出现的时间和区域,并对其动态响应随当量、爆距及水深的变化规律进行研究。利用数值拟合方法得到航行体表面动态应力方程,并通过决定系数验证其可靠性,在定当量、爆距情况下可直接求解其动态应力。研究结果表明:当量增加,动态应力在相同爆距区间内衰减速率增大;爆距增大,动态应力在相同当量区间内增长速率降低;深度每下降100 m,动态应力增长20 MPa左右。所得研究结果可为中远场水下爆炸作用下航行体安全防护和抗冲击研究提供一定参考。

基于反相法的中场校准技术研究

在相控阵天线研制中,阵面校准是非常重要的一环。对比各种校准方法,中场法使用设备少、测试效率高,因而获得了广泛的应用。通常情况下,阵面中的T/R组件内设计有三态开关(发射态、接收态、负载态),中场测试时,通过“逐路通”的方式(逐一选通T/R组件的射频通道,非被测通道处于负载状态),得到所有通道的发射通道(或接收通道)的幅相数据。但在“芯片化”T/R组件组成的阵面中,开关隔离度有限,泄露信号严重干扰被测信号,甚至无法进行正常的故障判断。本文讨论一种基于反相法的中场校准方法,分析了该方法的误差量级,最后通过远场波瓣测试验证了该方法的有效性。

基于电荷耦合效应的超级结JBS二极管的仿真分析

为提升现代单极型功率二极管的性能,进一步突破“硅极限”,通过加大传统JBS二极管中P+区结深,引入超级结结构以减薄芯片厚度,缓解传统单极型器件通态压降与反向阻断电压之间的矛盾,提高单位面积器件的导通电流密度。使用数值方法分析了超级结JBS二极管中P柱区浓度、N柱区宽度和N柱区浓度对正向导通特性以及反向阻断特性的影响,应用电场耦合效应理论分析了超级结JBS二极管的正向导通和反向阻断机理,设计了一款300 V的超级结JBS二极管。

若羌阿亚克稀有金属矿田成矿地质条件及找矿前景分析

新一轮找矿突破战略行动以来,阿尔金地区稀有金属矿取得重大找矿突破,陆续发现评价了阿亚克、瓦石峡南、库木萨依、塔什达坂等4个具有大型远景的稀有金属矿田。阿亚克稀有金属矿田位于阿尔金山中段,大地构造位置属秦祁昆造山系阿尔金古生代造山带阿中地块[1]。地层属塔里木-南疆地层大区阿尔金小区,主要出露地层为古元古界阿尔金岩群及英格里克构造蛇绿混杂岩中部复理石。侵入体为青白口纪、奥陶纪侵入体。发育有466条伟晶岩脉,产于英格里克构造蛇绿混杂岩复理石岩片黑云斜长石英片岩及阿尔金岩群片岩、片麻岩中,稀有金属矿化伟晶岩空间分带特征明显,矿化类型具北铍-中锂-南铍特征。主要控矿断裂为卡尔恰尔-阔什区域性大断裂(阿中断裂)。区内圈定稀有金属相关的1∶5万化探综合异常9处,异常与矿点对应好,均为矿致异常。矿田内已发现阿亚克、吐格曼2处中型锂铍稀有金属矿床,阿亚克矿床圈定67条矿体,矿体地表出露规模较小,深部隐伏相连,延伸稳定。吐格曼矿床圈定矿体12条。矿田成矿条件、成矿背景优越,找矿前景较好。

基于伪解析法的TTI介质纯qP波地震波场正演模拟

近年来,各向异性介质纯qP波正演模拟及逆时偏移成像技术受到广泛关注。常规拟声波方程存在伪横波干扰、受模型参数限制(ε≥δ)、传播不稳定和计算精度不高等因素影响,极大地限制了其应用。为此,本文将qP波拟微分方程变换到空间—波数域,并通过坐标变换,推导了时间域TTI介质二阶纯qP波波动方程;为提高计算精度,引入伪解析算法(pseudo analytical method, PAM),实现了基于伪解析法的TTI介质纯qP波地震波场正演模拟。数值模拟结果表明:(1)本文方法克服了拟声波方程的局限性,消除了伪横波干扰,不受模型参数限制且地震波场能稳定传播;(2)与其他方法相比,伪解析法能有效提高数值模拟精度;(3)简单及复杂模型测试验证了本文方法的正确性与适用性。

“断层阴影”识别与校正方法——以松辽盆地升平构造为例

地层错断往往引起速度横向突变,导致在时间域地震资料中出现“断层阴影”现象,影响地质解释结果及圈闭评价等。为此,以松辽盆地升平构造为例,分析“断层阴影”现象,提出了正演模拟法、井震结合地层对比法和平均速度成图法三种识别方法;在此基础上,针对“断层阴影”,提出了高精度速度场校正和时间域层位校正两种校正方法。结果表明,高精度速度场校正法可以实现数据体的校正,适应性更广;时间域层位校正法可以实现层位的校正,具有快速、简便的优势。该方法对类似地区具有借鉴意义。

哈萨克斯坦南图尔盖盆地Doshan斜坡带岩性油气藏储层预测方法

综合利用钻井、测井、地震等资料,分析了哈萨克斯坦南图尔盖盆地Doshan区块中部斜坡带沉积特征,并提出了一种岩性油气藏储层预测方法,识别出岩性圈闭,地震属性分析验证了储层预测结果的可靠性。研究结果表明:(1)哈萨克斯坦南图尔盖盆地Doshan斜坡带中—下侏罗统沉积时构造活动强烈,发育少量断裂,以湖相沉积为主,可分为SQ4—SQ6共3个沉积期,分别对应埃巴林组(J_(1)ab)、多尚组(J_(2)ds)和卡拉甘塞组(J_(2)kr),SQ6时期发生大规模湖侵,扇三角洲呈裙带状展布在边缘断层一侧,半深湖范围扩大;三角洲前缘为岩性圈闭发育的有利相带。(2)储层预测方法为以井-震标定结果确定地层界线,以基于声波曲线重构的岩石物理分析校正井径的影响,以基于调谐厚度的正演模型分析识别砂体,以高分辨率岩性储层地震反演技术对单砂层进行识别。(3)研究区岩性圈闭主要分布于中—下侏罗统,发育于坡折控砂条件下的一系列构造带上。地震属性分析结果与沉积特征吻合度较高。(4)研究区中—下侏罗统的坡折位置发育一系列岩性圈闭,在高分辨率地震剖面上表现为强振幅、高阻抗特征,是勘探有利区。