Effect of cooling rate on solidification structure and linear contraction of a duplex stainless steel

Cooling rate is a key factor that can drastically affect the phase transformation and thermal stress of duplex stainless steels. Therefore, in this research, different sand moulds were used to explore the influence of cooling rate on the solidification of the 2304 duplex stainless steel (DSS). The macro and micro structures of the 2304 DSS were investigated. Small equiaxed grains are obtained in chromite sand mould sample with a lower pouring temperature and a higher cooling rate, whereas coarse columnar and equiaxed grains are found in silica sand and refractory powder mould samples. The size of austenite phase is significantly increased with decreasing cooling rate, while the ferrite phase content ranging from 51.6% to 53.9% does not change obviously. In addition, the linear contraction of the 2304 DSS decreases from 2.34% to 1.09% when the mean cooling rate above 1,173 K increases from 0.99 K·s-1 to 3.66 K·s-1.

A Probe into the Mortgage Rates of Land Contract Management Rights Based on Unified Annual Output Value

The mortgage of land contract management rights has launched a pilot project in Ningxia,Hubei,Henan,Guizhou,Chongqing and other provinces,municipalities and autonomous regions,which provides a good solution to the problem of funds for rural development and plays a huge role in promoting local rural economic development.In the mortgage financing of land contract management rights implemented in various regions,how to determine a scientific,accurate and reasonable mortgage rate of land contract management rights becomes a difficulty troubling the mortgage financing of land.On the basis of unified annual output value of land,this article uses survey method,income capitalization method,and comparison method to analyze the value of land contract management rights,and finally determine the mortgage rates of land contract management rights.

PVA-ECC材料抗压强度及收缩性的时变规律研究

PVA-ECC材料的长期力学性能对港口工程结构加固修复至关重要。通过PVA-ECC材料不同龄期试块的抗压强度试验和收缩性试验对其宏观力学特性的时变规律进行了研究。研究表明,2%PVA掺量的PVA-ECC材料的流动性差,其在港口水工结构加固工程中的适用性有待进一步研究。通过抗压强度试验可知,随着龄期的增加,1.5%PVA掺量和1.8%PVA掺量的试块抗压强度呈现抛物线上升的趋势,经180d养护后的试块抗压强度分别达到69.4 MPa和76.1 MPa,是C40混凝土试块强度的1.5倍和1.6倍,从抗压强度分析,两者均满足加固工程的强度要求。根据材料收缩性对比试验可知,随着龄期的增加,三种试块的收缩率在0~28 d期间变化剧烈,在28d后变化均趋于平缓,不同PVA掺量的试块收缩率均大于C40混凝土试块,而1.5%PVA掺量的试块与C40混凝土试块收缩率更接近。鉴于1.5%PVA掺量的PVA-ECC材料流动性更能适应沿海港工结构加固的现场施工,同时,其收缩率与混凝土收缩率接近,且抗压强度足够高,因此,在港口工程结构加固修复中,推荐采用1.5%PVA掺量的PVA-ECC材料。同时,基于试验数据拟合得到了适合不同配比、不同龄期PVA-ECC材料的立方体抗压强度计算公式,可用于PVA-ECC材料的强度预测。

Study on the Predicting System of Breaking Chip When PCD Tool Cutting Aluminum Alloy

In the field of automobile manufacture, during the aluminum alloy cutting, chip forming and breaking process are very complicated. It is affected by many facto rs. Automatic machining process can not be carried through if the chip enlaces t he workpiece or the tool. So the chip control and breaking are key technology. P CD tool has many traits, such as high cutting efficiency, machining precision an d wearability. It is desired that it be used for machining coloured metals.The p aper present the study of prediction of chip breaking when PCD Tool cutting alum inum alloy with chip breaker. In the process of cutting, the method of chip brea king is up-curl-dominant chip. Therefore, based on the theory of chip breaking with chip breaker, used the cutting condition of chip breaking, this paper dedu ce the chip breaking mathematical model when cutting aluminum alloy, that is to say, the chip breaker parameters(Angle of chip break,chip groove width, bevel a ngle, the normal rake angle of chip groove, tool cutting edge angle)influence th e critical feed rate. The following conclusion can be made from theoretic analys is. The critical feed rate will decrease when the Angle of chip break and bevel angle and the normal rake angle of chip groove and tool cutting edge angle incre ase. The critical feed rate will increase when chip groove width increase. The e xperimental results are well coincided with the theoretic ones, it is proved tha t the predicting system is correct.

对高维Schwarzschild-de Sitter黑洞视界处Fermions量子隧穿辐射率的修正

根据Lorentz-breaking理论对弦量场作用量进行修正并应用变分原理得到了高维Schwarzschild-de Sitter黑洞时空中的费米子动力学方程。通过对此动力学方程的研究得到了高维Schwarzschild-de Sitter黑洞事件视界处和宇宙视界处的量子隧穿率的修正形式,从而研究了此黑洞事件视界处和宇宙视界处的修正形式的Hawking温度和Bekenstein-Hawking熵的新的表达式。在得到研究结果的基础之上,文中最后还对研究方法和结论进行了讨论。

Foetal heart rate variability frequency characteristics with respect to uterine contractions

Monitoring foetal health is important to appropriately plan pregnancy management and delivery. Cardiotocography (CTG) is one of the most employed diagnostic techniques. Because CTG interpretation still lacks of complete reliability, new methods of interpretation and parameters are necessary to further support physicians’ decisions. To this aim, indexes related to variability of foetal heart rate (FHRV) are particularly studied. Frequency components of FHRV and their modifications can be analysed by applying a time-frequency approach, which allows for a distinct understanding of the spectral components related to foetal reactions to internal and external stimuli and their change over time. Being uterine contractions (UC) strong stimuli for the foetus and his autonomic nervous system (ANS), it is worth exploring the FHRV response to UC. This study analysed modifications of FHRV frequency characteristics with respect to 108 UC (relative to 35 healthy foetuses). Results showed a statistically significant (t-test, p < 0.01) power increase of the FHRV in both LF and HF bands in correspondence of the contractions. Moreover, we observed a shift to higher values of the maximum frequency contained in the signal corresponding to the power increase. Such modifications of the FHRV power spectrum can be a sign of ANS reaction and therefore represent additional, objective information about foetal reactivity and health during labour.

Comparison on global supply chain purchasing strategies based on supply contracts

In the global supply chain in a setting characterized by exchange rate uncertainties,it is quite necessary to focus on comparative research trying to find out which kind of purchasing strategy is better in different situations.The two common global purchasing strategies,risk sharing(RS)and quantity flexibility(QF),are selected to be compared.Using a real-options approach,the valuation models of RS and QF purchasing contracts are established.By means of binomial lattice technique,numerical simulation and sensitivity analysis of two stochastic dynamic programs are presented.The effects on expected discounted value by changing relative parameters are described clearly.Based on comparative analysis,it is concluded that the QF purchasing strategy is better than that of the RS especially where great volatility exists for exchange rate processes in the global supply chain.

The Effect of Strain Rate on Tensile Properties of Cotton Yarns

The effect of strain rate on tensile properties of cotton yarns is analyzed using the standard linear solid model. The tensile curve, breaking strength and work of rupture of the yarns under different strain rate are calculated. A good correlation exists between the experiment results and theoretical anticipations.

Mechanism of drilling rate improvement using high-pressure liquid nitrogen jet

To address the high rock strength and low drilling rate issues in deep oil/gas and geothermal exploitation, we performed mechanical property tests on three kinds of rock samples(granite, shale and sandstone) subjected to liquid nitrogen(LN2) cooling and conducted rock-breaking experiments using LN2 jet. Rock-breaking characteristics and mechanisms of LN2 jet, heat transfer features between LN2 and rock and thermal stress evolution in rock were analyzed. A novel high-pressure LN2 jet assisted drilling method was proposed accordingly. The study results show that LN2 thermal shock can significantly reduce uniaxial compression strength and elastic modulus of rock. Rock damage and corresponding mechanical deterioration become more pronounced with increasing rock temperature. The LN2 jet has merits of high rock-breaking efficiency and low threshold rock-breaking pressure. Rock failure under LN2 jet impact is characterized by large volume breakage and the rock-breaking performance becomes more significant with increase of rock temperature. Under the impact of LN2 jet, the damage of granite is the most remarkable among the three rock samples. Thus, this method works better for high temperature granite formations. It has a good application prospect in speeding up drilling rate in deep hot dry rock geothermal reservoirs.

Determination of Variables That Affect the Remission Rate of Sewing Operations in a Textile Company

In operations management, the learning curve has been an effective tool in estimating operator performance. However, discontinuities in work disrupt the learning process and a phenomenon called remission or forgetting occurs, resulting in increased time of performing the task upon resumption of work. The study aims to identify variables that significantly affect the remission rate of sewing operations in a manufacturing setting. Four variables--length of stint 1, percent Differenceat stint t, gender, and product family, were identified. Statistical analyses, such as paired t-test, correlation, regression, and analysis of variance （ANOVA） were conducted in order to observe the relationships between the dependent variable and independent variables. For the results of the first general regression, gender was found to be an insignificant variable in predicting remission rate, while product family, length of stint 1, and percent Differenceat stint I were statistically significant. Moreover, the final general regression, which excluded the insignificant gender variable and considered the （regrouped） product families, revealed that product family, length of stint 1, and percent Differenceat stint 1 were still statistically significant. Length of stint 1 had a moderately positive correlation with remission rate, while percent Differenceat stint i had a moderately negative correlation with remission rate. Also, percent Differenceat stint 1 was the largest contributor to the remission rate model. In terms of R2, the goodness-of-fit of the model is moderate. Finally, the model yielded an absolute error of 5.08%, indicating a high accuracy in predicting remission rate.

HRV changes before and after radiofrequency ablation in patients with different origin of right ventricular outflow tract ventricular premature contraction

Objective:To observe the HRV changes before and after the radiofrequency current catheter ablationventricular premature beats originated from different site of right ventricular outflow tract.Methods:A total of 102 patients with frequent RVOT-VPC admitted to our hospital were accepted radiofrequency current catheter ablation (RF). According to the origin of RVOT-VPC, it was divided into 2 groups, one is from ventricular septum, and the other one is from free wall, and in each group, male and female are observed separately.Results:(1) HRV before RF ablation: 1) rMSSD in the female patients with RVOT-VPC from free wall was significantly lower than those from septum;2) frequency domain index (W, LF) were higher than normal range, and in male patients, LF/HF<1 were found, but in female patients, LF/HF>1. (2) HRV after RF ablation: 1) Significant changes were found in female patients with RVOT-VPC from septum, rMSSD, PNN50, HF and LF decreased;2) In female patients with RVOT-VPC from free wall, rMSSD decreased;3) In male patients, there were no significant HRV changes found before and after RF ablation. (3) Heart rate changes: 1) In female patients with RVOT-VPC from septum, heart rate decreased significantly ((76.47±9.47) bpm vs (69.29±14.59) bpm)2) No significant changes were found in male patients.Conclusion:In patients with RVOT-PVC sympathetic and vagus excitability increased, and after catheter ablation, in female patients with RVOT-PVC originated from septum, the HRV index relating to sympathetic and vagus excitability significantly decreased.

热释放解堵剂ThermAcid的室内研究

针对海上弱凝胶完修井液泥饼破除存在的作用深度有限、不能有效清除固相污染等问题,开发了ThermAcid热释放解堵剂。ThermAcid具有水溶性,且可缓慢水解释放出酸,因而能够有效地清除储层深部的污染物。水解动力学研究表明,ThermAcid的水解速度随pH值增大、温度升高而加快,碳酸钙溶蚀实验证实了上述规律。腐蚀速率实验表明:120℃下,ThermAcid对钢片的腐蚀速率为2.31 g/(m^(2)·h),低于5%盐酸对钢片的腐蚀速率(8.31 g/(m^(2)·h)),有利于缓解井下钻具腐蚀。30 mD和400 mD砂盘破胶实验表明:与5%盐酸相比,ThermAcid破胶更均匀、更彻底,因而返排压力更低。

Response of slope surface roughness to wave-induced erosion during water level fluctuating

The bank slopes in hydro-fluctuation areas of reservoirs or lakes suffer from severe erosion due to an absence of protection. Waves are one of the important external forces that cause bank erosion and slope failures. However, the processes and quantified impacts of wave-induced erosion on slopes remain unclear under different water level-fluctuation conditions. This paper focuses on the characteristics of wave-induced slope erosion under three conditions: water level dropping(WLD), fixed(WLF) and rising(WLR). A steel tank with glass pane was used to simulate the wave-induced slope erosion in the three treatments. The slope elevation data were collected by using the method of the pin meter for every 15 minutes from the beginning to the end, a total of 5 times during all treatments. These data were processed by using software(SURFER 9.0) to get the slope micro-topography and the erosion volume. Then the temporal and spatial change of slope erosion was analysed according to the erosion amount or erosion rate calculated based on bulk density of slope soil. The results demonstrated that the soil erosion rates for different water level changing treatments are in the following order: WLR>WLD>WLF. For the erosion spatial variation, the middle part of the slope was the major source of sediment in the WLD. The upper part of the slope was the major source of the sediment for the other two treatments. Compared with the standard deviation(SD), the coefficient of variation(CV) based on the SD is more representative of variations in the soil surface roughness(SSR). Furthermore, the good fit between the SSR and soil erosion rate have the potential to be used to predict soil erosion. Above all, the injection angle of the wave determined the rate of erosion to some extent, and the fall-back flow of the wave could also influence the extent of erosion, deposition, and bank morphology. It is vital to choose the appropriate index(SD or CV) in the three water levels to improve the prediction accuracy. This paper could provide scientific knowledge to manage reservoirs or river banks.

Modelling the Iranian Petroleum Contract fiscal regime using bargaining game theory to guide contract negotiators

Based on Iran's sixth development plan,the country's oil and gas industry requires an investment of about$200 bn in the next five years to increase production.The Iranian government,to attract and motivate international oil company investment in their oil and gas fields,has presented a new type of risk service contract:the Iranian Petroleum Contract(IPC).This paper summarizes the features of the IPC and presents mathematical models of its fiscal regime for the benefit and guidance of both the National Iranian Oil Company(NIOC)and the contractors.Next,adopting bargaining game theory provides a mathematical model for reaching a win-win situation between the NIOC and the contractor.Finally,a numerical example is given and a sensitivity analysis performed to illustrate the implementation of the proposed models.The contractor and the NIOC may use these models when preparing their proposal and in the course of actual negotiations to calculate their internal rate of return,remuneration fee,and net present value for developing the fields at different conditions of their bargaining power,and derive a logical bargain to protect their best possible interests.

A Comparative Study of Performance Between Operators With Work Discontinuity and Without Work Discontinuity

In situations where discontinuity in operation occurs, specifically in a country where coontractualization has an increasing trend, the performance level of operators after the work break is of great interest. Existing studies have found that the performance of an operator declines after her operation is completely stopped. However, when the operator performed other tasks （may it be similar or not from her previous task） during the work break, the performance after the work break seems to be affected at different level. Contractual and regular operators from a semiconductor and textile company were considered to replicate a discontinuous and continuous operation. The processing times of contractual workers before and after several months of work break were compared. Two types of work break were seen to have significant effect on an operator＇s performance after the work break, Type 1： 0% to 40% similarity from previous task and Type 2： 40% to 97% similarity from previous task. One can find that when 21% of tasks performed during the work break are similar to the operator＇s previous task, there would be no change in her performance upon returning. On the other hand, a 5% decline in performance was observed after work break type 1 and an 8.54% improvement after work break type 2. Also, a remission rate of 18% from end of stint 1 to start of stint 2 under work break type 1 was seen, while 8% for work break type 2. This may also be true to other industries. Thus, further study is suggested.

Automatic &Safe Oxytocin Induction of Labor

Aims: To prevent fetal damage by excess oxytocin administration of manually controlled infusion, by automatic and safe increasing infusion setting with monitoring uterine contraction and fetal heart rate. Methods: Starting infusion level was 2 milliU/ml, as oxytocin sensitivity of a pregnant uterus is unknown, to avoid hyper contraction and fetal bradycardia caused by unexpected excess oxytocin sensitivity. The infusion automatically increased with automatic monitoring of uterine contraction curve, then the increasing stopped when contraction reached to normal labor level, where the infusion level maintained, which continued until delivery, if there is no trouble. However, the infusion continued until expiring all fluid in case of insensitive uterus, where the induction was performed in another day. The infusion stopped automatically when contraction was too strong, or fetal heart rate is abnormal. Thus, oxytocin sensitive case is protected from excess contraction and fetal asphyxia. Results: Normal vaginal delivery was achieved in 28/33 cases (85%), which was more than manually controlled infusion. No case was abnormal in successful oxytocin infusion. Conclusion: The automated technique will be applied to oxytocin labor induction.

Atypical Intrapartum Maternal Heart Rate Pattern in a Woman with Paroxysmal Supraventricular Tachycardia

Pregnant women show characteristic hemodynamics, and their heart rates ordinarily increase with uterine contractions during labor. Conversely, uterine contraction-associated decelerations of maternal heart rate (MHR) are rare. We present a pregnant woman with paroxysmal supraventricular tachycardia (PSVT) who exhibited intrapartum MHR deceleration pattern. We performed simultaneous fetal heart rate monitoring with an external ultrasound transducer and MHR monitoring with a tocogram during her parturition. She developed a PSVT exacerbation in the second stage of parturition. As revealed by cardiotocography, the MHR baseline abruptly declined at onset of uterine contractions during the active phase of labor. Recovery followed, and the contraction resolved. The tachycardia got prolonged as the labor advanced. Our patient exhibited the unusual, up-and-down changes of the MHR pattern associated with labor contractions. The etiology of the occurrence of uterine contraction-associated MHR decelerations was unclear in the present case. Continuous tracing to visually inspect MHR patterns during parturition is a simple method for examining real-time MHR status of patients treated within obstetric practice settings.

The Efficiency of Non-repayable Funding Against Crisis Effects in Romania

The current economical crisis pointed out the gaps and the weak development of the Romanian economical system. If we were to compare the economy of a country to the human body then we would realize that constant and massive loss of ＂blood＂ may eventually lead to collapse of the economical system, which require Romania to speed up financial ＂transfusions＂. In these conditions, the most accessible and inexpensive source of funding is the non-repayable funding that Romanian economy can acquire by the year of 2013. In this paper we analyze the evolution of non-repayable funds allocated to Romania, in terms of those funds for the approved projects （their implementation has not yet started） but also in terms of those contracted projects or in the process of running （in fact representing ＂the necessary＂ amount of money that the Romanian economy needs）. The first part of the paper contains an overview of the situation about the requiring and the absorption of non-repayable funding since 2007 （officially since the crisis emerged in the U.S.） to present, also making an analysis of the influence they had on the Romanian economy. We take into account in this analysis that the effects of the crisis in Romania began to be felt in the second half of 2008, economical politics against crisis were not taken into accounted by this date. In this analysis we started from the assumption that one anti-crisis policy, taken into account by public decision members in Romania, is to increase efficiency and absorption of funds by raising the capacity of the Romanian economical environment for the implementation （and not only the winning ） of these funds. The second part of the paper contains an econometrieal development model which highlights the influence of changing the interest rates and exchange rate on the rate of contracting projects during January 2007-March 2010. The Analysis of the results emphasizes the stronger influence of the changing rate on the approved contracting projects compared with the changing influence of the reference interest rate. Following the results of the analysis we highlight the main reasons for which this economical policy of attracting and using outstanding funding represents until now, a failure more than a success. Also we present these several solutions to increase the volume of financial ＂transfusion＂ with a direct impact on the Romanian economy, arguing that such measures cannot be implemented without real political will from decision-makers in Romania.

On the Blow-up Phenomena of Cauchy Problem for the Camassa-Holm Equation

We focus on the blow-up phenomena of Cauchy problem for the Camassa-Holm equation. Blow-up can occur only in the form of wave-breaking, i.e. the solution is bounded but its slope becomes unbounded in finite time. We proved that there is such a point that its slope becomes infinite exactly at breaking time. We also gave the precise blow-up rate and the blow-up set.

Exploiting Virtual Elasticity of Production Systems for Respecting OTD-Part 1: Post-Optimality Conditions for Ergodic Order Arrivals in Fixed Capacity Regimes

Respecting the on-time-delivery (OTD) for manufacturing orders is mandatory. This depends, however, on the probability distribution of incoming order rate. The case of non-equal distribution, such as aggregated arrivals, may compromise the observance of on-time supplies for some orders. The purpose of this paper is to evaluate the conditions of post-optimality for stochastic order rate governed production systems in order to observe OTD. Instead of a heuristic or a simulative exploration, a Cartesian-based approach is applied to developing the necessary and sufficient mathematical condition to solve the problem statement. The research result demonstrates that increasing speed of throughput reveals a latent capacity, which allows arrival orders above capacity limits to be backlog-buffered and rescheduled for OTD, exploiting the virtual manufacturing elasticity inherent to all production systems to increase OTD reliability of non JIT-based production systems.