Seismic tomography of Yunnan region using short-period surface wave phase velocity

利用云南数字地震台网23个台站记录的短周期(1～18s)面波资料，用双台窄带通滤波互相关方法，测定了在209条路径上的基阶瑞利波相速度频散曲线，并通过层析成像反演得到各周期的相速度分布图象．给出了沿24°N，25°N，26°N及27°N和100．5°E的相速度频散剖面图．结果表明：云南地区的相速度分布图象具有强烈的横向变化，短周期段的相速度分布与沉积层厚度密切相关，中甸、丽江东部区域在约25km深度存在着明显的低速层，而畹町、云县、思茅一带在该深度范围是一明显的大面积高速区域．小江断裂与红河断裂围成的川滇菱形块体南段为低相速度区域．云南地区强震震中位置主要分布在相速度高速与低速过渡的区域．

Seismic tomography of Yunnan region using short-period surface wave phase velocity

The data of short-period (1~18 s) surface waves recorded by 23 stations belonging to the digital seismic network of Yunnan Province of China are used in this paper. From these data, the dispersion curves of phase velocities of the fundamental mode Rayleigh wave along 209 paths are determined by using the two-station narrowband filtering cross-correlation method. Adopting tomography method, the distribution maps of phase velocities at various peri-ods in Yunnan region are inverted. The maps of phase velocities on profiles along 24N, 25N, 26N, 27N and 100.5E and the distribution maps of phase velocities at 3 periods in the study region are given. The results show that the phase velocity distribution in Yunnan region has strong variations in horizontal direction, and the phase velocity distribution in short-period range is closely related to the thickness of sedimentary layers in the shallow crust. The phase velocity in southern part of the Sichuan-Yunnan rhombic block encircled by the Honghe fault and Xiaojiang fault is obviously lower than that in surrounding areas. The epicentral locations of strong earthquakes in Yunnan region are mainly distributed in transitional zones between low and high phase velocities.

New theoretical analysis method for the phase center in the Fresnel region of complex structure antennas

A finite domain time difference （FDTD） and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD＇s near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center. The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods＇ requirements for the radiation analytical formula of some complex antennas, which makes the existing second-derivative method more applicable in engineering. Also, FDTD increases the precision owing to the superposition field calculation from its extrapolation. The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.

Heptad Phase Vortex Array in Extremely Deep Fresnel Diffraction Region Generated by Asymmetrical Metal Subwavelength Holes Film

We report a heptad vortex array structure in the wave fields in an extremely deep Fresnel diffraction region by asymmetrical subwavelength holes in a metal film illuminated with linearly polarized light. A Mach Zehnder interferometer with a microscopic objective is used to record the wave fields at different distance＆ and the phase maps are extracted by Fourier transform of the interference intensities. We study the evolutions of the heptad vortex array with distance from the sample to the object plane. To explain the formations and the evolutions of the vortex array, we calculate the diffracted wave fields with Kirchhoff＇s diffraction theory. The calculations are basically consistent with the experimental results, and the properties of the heptad vortex array structure are reasonably explained.

(α+β)Dual Phase CuZnAl Shape Memory Alloy

The effect of α phase on CuZnAl shape memo- ry alloy(SMA)has been systematically studied by electrical resistance method,quantitative measure- ment of micrography and transmission electron microscopy(TEM).It is found that,by controlling the amount of α phase in(α+β)-CuZnAl alloy, phase transformation temperatures can be adjusted precisely in a wide range,while the good shape memory effect of CuZnAl is kept.In a word, quenching from(α+β)dual phase region is a rea- sonable method of adjusting phase transformation temperatures for CuZnAl alloy.

Partial phase relationships of Mg-Zn-Ce system at 350 ℃

The alloys were prepared in Mg-rich corner of Mg-Zn-Ce system. Partial phase equilibrium relationships of these alloys at 350 ℃ were identified by using scanning electron microscopy(SEM), electron probe microanalysis(EPMA), X-ray diffraction(XRD) analysis and selected area electron diffraction(SAED) pattern analysis of transmission electron microscopy(TEM). Partial isothermal section of Mg-Zn-Ce system in Mg-rich corner was identified. The results show that there is one ternary compound (T-phase) in Mg-Zn-Ce system. The T-phase is a linear ternary compound in which the content of Ce is about 7.7% (molar fraction); while the content of Zn is changed from 19.3% to 43.6% (molar fraction). The crystal structure of T-phase is C-centered orthorhombic. In addition, one two-phase region of Mg+T-phase and one three-phase region of Mg+T-phase+MgZn(Ce) exist in the Mg-rich corner of Mg-Zn-Ce system at 350 ℃.

Long-term results of paclitaxel plus cisplatin with concurrent radiotherapy for loco-regional esophageal squamous cell carcinoma

AIM To evaluate the long-term effectiveness and late toxicities of paclitaxel(PTX) plus cisplatin(DDP) with concurrent radiotherapy for locally advanced esophageal squamous cancer.METHODS Between 2008 and 2011, 76 patients were enrolled in a phase Ⅱ study on the treatment of loco-regionally advanced esophageal cancer with radiotherapy(68.4 Gy/44 fractions or 61.2 Gy/34 fractions) combined with 4-cycle chemotherapy consisting of DDP(25 mg/m^2 per day for 3 d) and PTX(175 mg/m^2 for 3 h). The primary endpoints were overall survival and progression-free survival, and the secondary endpoints were toxicity and the treatment failure pattern.RESULTS A total of 76 patients were enrolled in this study, of whom 63.2% finished the whole regimen. The 5-year survival rates for the per-protocol population and intent-to-treat population were 25.4% and 26.4%, respectively, and the median survival rates were 23.7 mo and 28.5 mo, respectively. Grade 3 or 4 late toxicity was observed in only one patient(heart failure). In log-rank analysis, the pretreatment stage(stage Ⅱ + Ⅲ: 36.1 mo vs stage Ⅳ: 14.9 mo) and the completed cycle(1-3 cycles: 16.1 mo vs 4 cycles: 35.5 mo) were significant prognostic factors(P = 0.037 < 0.05 and P = 0.013 < 0.05).CONCLUSION Radiotherapy combined with chemotherapy consisting of PTX and DDP is a safe and effective definitive treatment for loco-regionally advanced esophageal squamous cancer.

Shear wave anisotropy in D” region beneath the western Pacific

Using seismic shear phases from 47 Tonga-Fiji and its adjacent region events recorded by the CENC and IRIS, and from 26 northeast Asia and north Pacific events recorded by IRIS, we studied the shear wave anisotropy in D＂ region beneath the western Pacific utilizing the ScS-S differential travel time method and obtained the splitting time values between the radial and transverse components of each ScS wave corresponding to each core-mantle boundary （CMB） reflection point. We found that most shear waves involved horizontally polarized shear wave components traveling faster than vertically polarized shear wave components through the D＂ region. The splitting time values of ScS wave range from -0.91 s to 3.21 s with an average value of 1.1 s. The strength of anisotropy varies from -0.45% to 1.56% with an average value of 0.52%. The observations and analyses show that in the D＂ region beneath the western Pacific the lateral flow is expected to be dominant and the vertical transverse isotropy may be the main anisotropic structure. This structure feature may be explained by the shape preferred orientation of the CMB chemical reaction products or partial melt and the lattice preferred orientation of the lower mantle materials caused by the lateral flow at lowermost mantle.

STUDY ON AUSTENITE-FERRITE TRANSFORMATION WITHIN CRITICAL TEMPERATURE REGION

his paper deals with the phase trans formation of austenite to ferrite within the critical temperature region(between Ac1 and Ac3).The results show that the volume fraction of trans formation of ferrite formed isothermally from austenite is mainly varied with the austenitizing temperature.The higher the austenitizing temperature,the more volume fraction of the ferrite formed isothermally from austenite.Besides,the phase trans formation of austenite to ferrite within the critical temperature region was checked by austenitizing isothermal time.The volume fraction of ferrite formed isothermally from austenite within the critical temperature region for different isothermal time has heen examined experimen tally.The lglg(l-fv)-1 vs lgt relation does not follow the Avrami equation strictly and consists of two straight lines.

A Thermal-Hydraulic Coolant Channel Module (CCM) for Single- and Two-Phase Flow

A theoretical “drift-flux based thermal-hydraulic mixture-fluid coolant channel model” is presented. It is the basis to a corresponding digital “Coolant Channel Module (CCM)”. This purpose derived “Separate-Region Mixture Fluid Approach” should yield an alternative platform to the currently dominant “Separate-Phase Models” where each phase is treated separately. Contrary to it, a direct procedure could be established with the objective to simulate in an as general as possible way the steady state and transient behaviour of characteristic parameters of single- and/or (now non-separated) two-phase fluids flowing within any type of heated or non-heated coolant channels. Their validity could be confirmed by a wide range of verification and validation runs, showing very satisfactory results. The resulting universally applicable code package CCM should provide a fundamental element for the simulation of thermal-hydraulic situations over a wide range of complex systems (such as different types of heat exchangers and steam generators as being applied in both conventional but also nuclear power stations, 1D and 3D nuclear reactor cores etc). Thereby the derived set of equations for different coolant channels (distinguished by their key numbers) as appearing in these systems can be combined with other ODE-s and non-linear algebraic relations from additional parts of such an overall model. And these can then to be solved by applying an appropriate integration routine. Within the solution procedure, however, mathematical discontinuities can arise. This due to the fact that along such a coolant channel transitions from single- to two-phase flow regimes and vice versa could take place. To circumvent these difficulties it will in the presented approach be proposed that the basic coolant channel (BC) is subdivided into a number of sub-channels (SC-s), each of them being occupied exclusively by only a single or a two-phase flow regime. After an appropriate nodalization of the BC (and thus its SC-s) and after applying a “modified finite volume method” together with other special activities the fundamental set of non-linear thermal-hydraulic partial differential equations together with corresponding constitutive relations can be solved for each SC separately. As a result of such a spatial discretization for each SC type (and thus the entire BC) the wanted set of non-linear ordinary differential equations of 1st order could be established. Obviously, special attention had to be given to the varying SC entrance or outlet positions, describing the movement of boiling boundaries or mixture levels along the channel. Including even the possibility of SC-s to disappear or be created anew during a transient.

数字经济、绿色技术创新与能源效率提升——基于城市面板数据的实证分析

提高能源效率是我国经济绿色转型和实现双碳目标的必然要求,当下数字经济已成为能源效率提升的新动能。本文基于数字经济的“四化”框架,在理论分析的基础上,运用2011~2020年我国284个地级市的面板数据,实证检验了数字经济影响能源效率提升的机制、特征和路径。结果表明:(1)数字经济及各维度对能源效率提升的总体效应为正,其中产业数字化促进作用最强,且数字经济对能源效率的提升具有区域异质性;(2)数字经济对能源效率的提升存在双门槛,呈现中间波动但总体促进的“N”型特征;(3)数字经济可通过促进绿色技术创新进而提升能源效率,且绿色技术创新水平的提高有助于城市跨越数字经济的第二个门槛,实现数字经济发展与能源效率提升的共赢。

寒区相变蓄热墙体多因素热特性研究

在墙体中应用相变材料可以显著改善墙体的保温蓄热能力,但相变材料厚度和墙体构造的选择尚需科学论证。基于寒区气象特点,选择适用于寒区建筑外墙的相变储能材料,从墙体的传热特性角度出发,通过建立不同相变材料层厚度和多种构造的相变墙体模型,研究多种情况相变墙体的热特性。结果表明,相变墙体在冬季的保温蓄热能力受相变材料层位置和厚度影响,夏季效果主要受相变材料厚度影响;相变材料厚度为40 mm的中间型相变墙体和相变材料厚度为60 mm的内侧型相变墙体比较适合寒区建筑应用。研究所得结论可为寒区相变墙体的结构设计优化提供参考。

影响山西台网地震定位因素的定量分析

基于山西地震台网现有的台站布局,利用数值模拟方法定量分析地壳速度模型、台网布局及震相拾取精度等因素对震源位置测定的影响,结果显示,3种因素对准确测定震源位置的影响不同。地壳速度模型中上地壳速度对震中位置的影响最大,而震中位置对莫霍面速度变化的反映更为灵敏。单独改变地壳速度模型引起的震中位置偏差通常不超过5 km,震源深度对地壳速度模型的变化十分敏感,尤其是莫霍面深度,最大偏差可能超过20 km。在不考虑其他因素的条件下,P波拾取精度在4 s以内测定的震中位置和震源深度最大偏差不超过2 km和5 km。当地壳速度模型适宜且震相拾取精度较高时,最大空隙角在0°~180°的台站布局对震源位置的约束较好,震中偏差基本小于1 km,震源深度偏差略大(约为2 km)。

Assessment of Health-Related Quality of Life of Tuberculosis Patients in Fako Division, South-West Region of Cameroon

Background: Tuberculosis (TB) caused by Mycobacterium tuberculosis is one of the top 10 causes of death worldwide. Despite the global impact of TB and treatment received, a gap persists between treatment and quality of life of the patients especially in resource limited countries. This study therefore evaluated the health related quality of life of TB patients and the different factors influencing their quality of life at the post intensive phase of their treatment in the Fako division of the South-West Region of Cameroon. Methods: A hospital based cross sectional study was carried out in 4 tuberculosis treatment centers, namely two regional (Buea and Limbe) and two district (Tiko and Muyuka) hospitals in Fako Division between June and July 2017. One hundred and sixty-seven TB patients were enrolled in the study and relevant information from them was gathered using the SF-36 questionnaire. Various aspects such as their perception of the disease, their socio-demographics and socio-economics conditions were evaluated. Results: Of the 167 participants enrolled in the study, 95 (56.9%) were male and 72 (43.1%) were female. One hundred and thirty-three (79.6%) of the 167 participants were affected by pulmonary tuberculosis and 34 (20.4%) by extra-pulmonary tuberculosis. Fifty-five (32.9%) were HIV positive and 90 (53.9%) had been receiving treatment for 4 - 6 months, 73 (43.7%) for 1 - 3 months and 4 (2.4%) for 7 - 9 months. The lowest and highest scores were recorded on the role limitation due to emotional problems scale (30.54 ± 35.36), and on the social functioning scale (47.68 ± 16.33) respectively. There was a significant difference (p = 0.021), between pulmonary and extra pulmonary tuberculosis (49.15 ± 16.08 vs. 41.91 ± 16.25) on the social functioning. Financial difficulty restraining drug collection affected the general health perception (p = 0.003), vitality (p = 0.007), emotional well-being (p < 0.001) and social functioning (p = 0.05) of the patients. Low income affected the vitality (p = 0.039), emotional well-being (p = 0.015), role limitations due to physical (p = 0.046) and emotional (p = 0.003) problems of the patients. Equally, the HIV status affected their vitality (p < 0.001) and emotional well-being (p = 0.011). Conclusion: The quality of life of the TB patients in the study area was generally poor. Counselling of diagnosed TB patients and provision of financial assistance through a social package can improve the acceptance of the disease during their treatment period to avoid default and relapse.

正癸烷/空气旋转爆轰波形成与传播数值模拟

针对气液两相旋转爆轰波形成与传播问题,本文以液态正癸烷为燃料,采用欧拉-拉格朗日方法,通过三维数值模拟给出了两相旋转爆轰波的形成演变特点和自持传播机理。研究结果表明:在起爆阶段,通过调控初始燃料分布能够获得强度不同的爆轰波和压力波;在对撞阶段,爆轰波与压力波共发生4次对撞,由于缺乏燃料供给,压力波逐渐衰减并消失,爆轰波以单波模态传播;在稳定传播阶段,未燃燃料在三叉点处聚集形成未反应气流区并诱导产生局部爆炸。未反应气流区的周期性出现和局部爆炸是两相爆轰波自持传播的重要影响因素。

SCM435冷镦钢的球化退火工艺

为获得球状珠光体以改善冷镦性能,对SCM435冷镦钢进行了亚温退火和亚温退火加两相区温度退火,前者为700℃保温4 h炉冷至580℃空冷,后者为700℃保温3.5 h,再升温至745℃保温0.5 h炉冷至580℃空冷。检测了退火后钢的显微组织、力学性能和冷镦性能。结果表明:经两种工艺球化退火后,SCM435钢的显微组织均为铁素体和球状珠光体,与热轧态相比断后伸长率和断面收缩率均提高、抗拉强度降低;经两种工艺球化退火的SCM435钢均能进行大变形率冷镦而不开裂。

不同钢种凝固模式的模拟分析研究

采用铸造模拟分析软件对3种6 t具有不同液固两相区温度区间的钢种进行了凝固过程的数值模拟分析。结果表明,不同液固两相区温度区间钢的凝固模式相差较大,按两相区温度区间的大小,其凝固模式呈现出由“U”型整体凝固模式向“V”型顺序凝固模式的转变。现场钢锭冒口解剖结果表明,一次缩孔深度与实际缩孔深度较相近,验证了模拟结果与现场试验结果具有较高的吻合度。

汽车用IF钢连铸坯第Ⅲ脆性区及其形成机理分析

探明连铸坯第Ⅲ脆性区及其形成机理对避免铸坯裂纹的产生、有效调控铸坯性能具有重要指导作用。采用Gleeble热/力模拟试验机对汽车用IF钢铸坯的高温力学性能进行了试验研究,结合热膨胀测试及组织分析手段,探究了IF钢铸坯第Ⅲ脆性区的形成机理。结果表明:IF钢的高温热塑性较优异,第Ⅲ脆性区温度范围为850~950℃,二冷低延性区为875~925℃,1250℃以上抗拉强度和屈服强度分别低于30 MPa和20 MPa,从变形和受力两个角度综合考虑,矫直区温度应控制在950~1250℃。第二相含量在950℃左右达到最高,大量微米级的TiN和少量TiN与MnS复合第二相会导致热塑性下降。950℃以下大量微米级第二相、A_(e3)温度附近形变诱导铁素体以及A_(ff)~A_(r3)温度范围内奥氏体分解的共同作用是导致IF钢连铸坯第Ⅲ脆性区形成的根本原因,不同冷速下IF钢铸坯二冷低延性区的温度范围与T_(α)^(40%)(C_(R))~A_(e3)基本一致。

Phase Unwrapping in Magnetic Resonance Elastography

Phase Unwrapping (PU) is an ill-posed problem in Magnetic Resonance Elastography (MRE). The phase information is not usable until the phases are retrieved by using PU algorithms. In this present study, we attempt to determine the ideal PU method for MRE using both phantom and volunteer psoas major (PM) muscle images. All the MRE experiments were carried out in Philips MRI (Achieva 3.0 T, Best, The Netherlands). A multi-echo gradient-echo MRE pulse sequence was employed and the four PU methods were considered based on their easy user platform. They are namely, Minimum Discontinuity (MD), Laplacian-Based Estimate (LBE), Region Growing (RG) and Dilate-Erode (DE) Propagate. Phantom images were successfully unwrapped by all four methods, whereas MD and LBE could only unwrap PM muscle images properly. RG and DE failed to unwrap the PM muscle images.

不同固溶处理对Cu-Cr系合金组织和性能的影响

热处理工艺调控是提升Cu-Cr系合金性能的有效方法。Cu-Cr系合金的固溶工艺大多选择温度较低的Cu-Cr两相区进行,导致Cr相固溶程度不完全,抑制后续析出强化效果。本研究提出采用高温单相区固溶工艺改善析出强化效果,主要研究不同固溶工艺(Cu-Cr两相区(950℃,4 h)和Cu单相区(1050℃,6h))对Cu-Cr系合金组织和性能的影响。采用电子探针(EPMA)对两种固溶工艺后的元素分布进行表征,并对峰值时效态合金的微观结构采用XRD和TEM进行表征分析。结果表明:与两相区固溶相比,单相区固溶后铸态Cr相充分固溶,时效过程中更多纳米Cr相弥散析出;合金力学性能相比两相区固溶后峰值时效态有较大提升,其中屈服强度提升29.3%,抗拉强度提升25.6%,而导电率并未明显下降。强度理论计算结果表明,析出强化所贡献的屈服强度增量为323.4 MPa,贡献56.9%,析出强化是本研究中最主要的强化机制。