HD 105020 is probably a long-period binary

Archer declared HD 105020 to be an Algol-type binary with a K-type main star and a period as short as two days. This, if confirmed, would be very significant. We made 21 observations of this star on three nights in 1984 using the 2.0-m telescope and Reticon system of McDonald Observatory, and 3 observations on two nights in 1991 using the 2.1-m telescope with TI2 CCD system of Kitt peak Observatory and found (1) that the radial velocity varied little over successive nights and the spin velocity to be small, hence it cannot be an Algol star with a two-day period and (2) that the radial velocity varied considerably at different times, and that the star could well be a spectroscopic binary with a period of about 20 days.     

Automatic seismic wave detection and autoregressive model method

The problem of automatic detection of seismic waves by large telemetered seismic networks such as the Mexican Continental Aperture Seismic Network (RESMAC), is extended here to include determination of seismic first-arrival and S-phase-arrival times. A short general outline of the detection problem background and a small introduction to the autoregressive model (AR) concept are presented. Several automatic detection algorithms were implemented and compared with a newly developed autoregressive algorithm. Careful consideration of the advantages and disadvantages of each method determined that a mixed detection scheme is optimal and suitable for RESMAC. A few examples are shown that illustrate the relative performances of the methods tried here. The proposed detection scheme has the following characteristics: (a) First-arrival detection, based on a simple (average of squared input) characteristic function, and a trigger criterion that uses as a distortion measure the long-average-to-short-average ratio of the characteristic function, checked using a duration criterion; (b) use of two threshold values, one for triggering, and another for beginning the backward search for the phase arrival time; (c) use of the autoregressive model (AR) method, with the Itakura-Saito distortion measure, for S-phase detection, checked using both duration and amplitude criteria; and (d) characterization of the reliability of the determinations for their subsequent use in automatic location programs, alarms, etc. The automatic detection scheme has proved effective.     

Natural occurrence of reidite in the Xiuyan crater of China

The high‐pressure minerals of reidite and coesite have been identified in the moderately shock‐metamorphosed gneiss (shock stage II, 35–45 GPa) and the strongly shock‐metamorphosed gneiss (shock stage III, 45–55 GPa), respectively, from the polymict breccias of the Xiuyan crater, a simple impact structure 1.8 km in diameter in China. Reidite in the shock stage II gneiss displays lamellar textures developed in parental grains of zircon. The phase transformation of zircon to reidite likely corresponds to a martensitic mechanism. No coesite is found in the reidite‐bearing gneiss. The shock stage III gneiss contains abundant coesite, but no reidite is identified in the rock. Coesite occurs as acicular, dendritic, and spherulitic crystals characteristic of crystallization from shock‐produced silica melt. Zircon in the rock is mostly recrystallized. The postshock temperature in the shock stage III gneiss is too high for the preservation of reidite, whereas reidite survives in the shock stage II gneiss because of relatively low postshock temperature. Reidite does not occur together with coesite because of difference in shock‐induced temperature between the shock stage II gneiss and the shock stage III gneiss.     

影响广播中波转播站防雷系统作用的几个关键技术

电台中波转播站多建于城市近郊区,由于天线高耸落雷几率高,因而易受雷击干扰。针对建站时原已通过防雷验收的转播站设施在投入使用后依然频遭雷击受损的状况,分析了其防雷系统的内在布设技术问题,认为广播中波转播站原有防雷系统的一些关键技术缺漏是遭雷击受损的主要原因,并从转播站的实际情况出发,提出了转播站防雷设计的几个关键技术问题的解决方法：接地网逐级分流、屏蔽馈线再加设外屏蔽环群技术以及不同的线路、不同系统保护的配合方法等,从而形成广播转播站完整的防雷保护系统框架。     

Predicting Sea Surface Salinity Using an Improved Genetic Algorithm Combining Operation Tree Method

The purpose of this study is to demonstrate the use of an improved genetic algorithm combining operation tree method (IGAOT) and apply it to monitor the salinity of the Taiwan Strait by using remote-sensing data. The genetic algorithm combining operation tree (GAOT) is a data mining method used to automatically discover relationships among nonlinear systems. Based on genetic algorithms (GAs), the relationships between input and output can be expressed as parse trees. The GAOT method typically has the disadvantages of premature convergence, which means it cannot produce satisfying solutions and performs satisfactorily when applied to only low-dimensional problems. Therefore, the GAOT method is enhanced using an automatic incremental procedure to improve the search ability of the method and avoid trapping in a local optimum. In this case study, an IGAOT is used to determine the relationship between the in situ data on the salinity of the Taiwan Strait and the data on the spectral parameters, seven wavebands, of a Moderate-Resolution Imaging Spectroradiometer (MODIS) sensor. The results indicate that the IGAOT model performs more favorably than do the GAOT and linear regression (LR₁ and LR₂) models, exhibits higher correlation coefficients, and involves fewer estimating errors. The results of this study indicate that the proposed technique is useful for estimating the Taiwan Strait salinity.     

Combined adaptive multiple subtraction based on optimized event tracing and extended wiener filtering

The surface-related multiple elimination (SRME) method is based on feedback formulation and has become one of the most preferred multiple suppression methods used. However, some differences are apparent between the predicted multiples and those in the source seismic records, which may result in conventional adaptive multiple subtraction methods being barely able to effectively suppress multiples in actual production. This paper introduces a combined adaptive multiple attenuation method based on the optimized event tracing technique and extended Wiener filtering. The method firstly uses multiple records predicted by SRME to generate a multiple velocity spectrum, then separates the original record to an approximate primary record and an approximate multiple record by applying the optimized event tracing method and short-time window FK filtering method. After applying the extended Wiener filtering method, residual multiples in the approximate primary record can then be eliminated and the damaged primary can be restored from the approximate multiple record. This method combines the advantages of multiple elimination based on the optimized event tracing method and the extended Wiener filtering technique. It is an ideal method for suppressing typical hyperbolic and other types of multiples, with the advantage of minimizing damage of the primary. Synthetic and field data tests show that this method produces better multiple elimination results than the traditional multi-channel Wiener filter method and is more suitable for multiple elimination in complicated geological areas.     

番禺市农业结构的转变及其效果

单一化的经济不利于充分利用资源,而多元化的经济不利于高效利用资源。为了充分而高效利用资源,应该根据区域资源的实际状况确定合理的区域农业结构和专业化程度。１９８０年以来番禺市农业结构调整的效果表明,农业结构专业化程度降低的幅度越大,结构转变的效率越低,专业化程度降低的幅度越小,结构转变的效率就越高。区域农业发展的方向应该是在具有比较优势的行业专业化发展,在专业化基础上逐步实现规模化、基地化和农工贸一体化。     

长株潭地区农业功能的时空变化特征及发展策略研究

以长株潭地区23个县市区为研究区域,分别从农产品供给功能、就业和社会保障功能、生态保育功能、文化传承和休闲功能构建评价指标体系,综合运用熵值法、多指标综合评价法和农业功能变化的时空差异诊断模型等方法对长株潭地区1998~2014年农业功能的时空动态变化特征进行研究,根据各地区功能特征提出农业功能发展调控策略。研究结果表明：① 长株潭地区农产品供给功能有大幅提升,其重心有向外进一步扩散趋势;长株潭地区核心区域劳动力就业与社会保障功能下降幅度较大;大围山、罗霄山脉等山地丘陵区生态保育功能优势进一步凸显;文化传承和休闲功能部分区域获得进一步发展,但空间变化差异较小。② 研究发现不同区域农业主导功能不同,根据各地区农业功能不同优势特征,结合自身特色因地制宜发展优势农业并提出相应的优化调控对策,从而为长株潭地区农业多功能发展与功能特征的识别及确定提供理论依据。     

Leak-off mechanism and pressure prediction for shallow sediments in deepwater drilling

Deepwater sediments are prone to loss circulation in drilling due to a low overburden gradient. How to predict the magnitude of leak-off pressure more accurately is an important issue in the protection of drilling safety and the reduction of drilling cost in deep water. Starting from the mechanical properties of a shallow formation and based on the basic theory of rock-soil mechanics, the stress distribution around a borehole was analyzed. It was found that the rock or soil on a borehole is in the plastic yield state before the effective tensile stress is generated, and the effective tangential and vertical stresses increase as the drilling fluid density increases; thus, tensile failure will not occur on the borehole wall. Based on the results of stress calculation, two mechanisms and leak-off pressure prediction models for shallow sediments in deepwater drilling were put forward, and the calculated values of these models were compared with the measured value of shallow leak-off pressure in actual drilling. The results show that the MHPS (minimum horizontal principle stress) model and the FIF (fracturing in formation) model can predict the lower and upper limits of leak-off pressure. The PLC (permeable lost circulation) model can comprehensively analyze the factors influencing permeable leakage and provide a theoretical basis for leak-off prevention and plugging in deepwater drilling.     

On the transplantation and cultivation ofKappaphycus alvarezii in China

A 2-year study onKappaphycus alvarezii (Doty) Doty introduced to Hainan Island from the Philippines in 1985 showed promising results. The average daily growth in weight reached 10% at a favourable temperature of about 26°C. Experimental results showed that timely cutting of the plant was an effective way to obtain new cuttings for cultivation and accelerate growth. New cuttings 0.05 kg in weight are suggested to be used as “seeds” and the old plant should be harvested. At present, artificial cultivation with a type of underwater raft applicable in places where there is strong wind will expand cultivation to more regions in Hainan Province. This paper was originally published in Chinese inOceanologia et Limnologia Sinica 19(5): 410–418, 1988. The plant under discussion wasEucheuma alvarezii Doty which was previously calledE. striatum in the article, and which now becomesKappaphycus alvarezii (Doty) Doty. To the original title, “in China” was added. Only the essence of the original article was presented.