Thermodynamics of accelerating and rotating black holes

Thermodynamics of a large family of black holes from electrovacuum solutions of Einstein’s equations is studied. This family includes rotating and non-accelerating black holes with NUT charge, and rotating and accelerating black holes. The surface gravity, Hawking temperature and the area laws for these black holes are presented. The first law of thermodynamics is also given. An interesting outcome of our analysis is the restriction obtained on the magnitude of acceleration for these black holes.     

A field study investigating the potential use of phosphorus combined with organic amendments on cadmium accumulation by wheat and subsequent rice

A field study was performed to determine the efficiency of diammonium phosphate (DAP) applied alone or combined with biochar, lignite, and farmyard manure (FYM) on growth and cadmium (Cd) accumulation in wheat and rice. Before crop sowing, different treatments were applied in the field such as a control (T₁), DAP alone (0.1%, T₂), DAP + lignite (0.05% each, T₃), DAP + FYM (0.05% each, T₄), and DAP + biochar (0.05% each, T₅). Afterwards, the wheat seeds were sown in the soil. At wheat postharvest, rice was sown without any further treatment. Raw effluent was applied as an irrigation source during the whole growth period of both crops since it is the common practice of the farmers of study area. It was revealed that the use of amendments enhanced the yield and photosynthesis but lowered the Cd contents in straw as well as grains of both crops. In both crops, the highest yield of straw and grain was found in DAP + FYM whereas the lowest Cd concentration was found in DAP alone. The ammonium bicarbonate-DTPA extractable Cd of post wheat and post rice soils were decreased while the soil pH and immobilization index were increased in all treatments as compared with the control. The present field study highlighted that the DAP + FYM can be effective in increasing yield with decreased Cd concentrations in crop grains.     

Adaptive state estimation of groundwater contaminant boundary input flux in a 2-dimensional aquifer

In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative.Adaptive state estimator(ASE)is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique,thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters.The ASE is particularly designed for a system that encompasses independent unknowns and/or random switching of input and measurement biases.The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE,which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10%in 2-dimensional problems.Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios.Results also show that ASE enjoys a better estimation performance than its competitor,Recursive Least Square Estimator(RLSE)due to its larger error tolerance in greater process noise regimes.ASE's inherent deficiency of being slower than the RLSE,resulting from the complexity of algorithm,was also noticed.The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.     

Thermodynamics of charged and rotating black strings

We study thermodynamics of cylindrically symmetric black holes. Uncharged as well as charged and rotating objects have been discussed. We derive surface gravity and hence the Hawking temperature and entropy for all these cases. We correct some results in the literature and present new ones. It is seen that thermodynamically these black configurations behave differently from spherically symmetric objects.     

Adaptive state estimation of groundwater contaminant boundary input flux in a 2-dimensional aquifer

In many circumstances involving heat and mass transfer issues, it is considered impractical to measure the input flux and the resulting state distribution in the domain. Therefore, the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative. Adaptive state estimator (ASE) is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique, thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters. The ASE is particularly designed for a system that encompasses independent unknowns and /or random switching of input and measurement biases. The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE, which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10% in 2-dimensional problems. Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios. Results also show that ASE enjoys a better estimation performance than its competitor, Recursive Least Square Estimator (RLSE) due to its larger error tolerance in greater process noise regimes. ASE’s inherent deficiency of being slower than the RLSE, resulting from the complexity of algorithm, was also noticed. The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.     

伊洛瓦底海豚被追逐时回声定位信号特征变化的初步分析

本文的研究基于文莱湾浅水域的一头野生伊洛瓦底海豚水声定位信号的调查数据。在记录期间,有一艘渔船突然开启发动机,惊扰了其附近的一头伊洛瓦底海豚,接着渔船开始两次连续追逐海豚。这期间海豚回声定位信号的变化情况被记录下来。当伊洛瓦底海豚受惊吓被追逐时,信号的声压级、每分钟嘀嗒声信号串的发生次数、每个嘀嗒声信号串中的脉冲个数和平均脉冲间隔都发生了相应的变化。平均的脉冲间隔在事件发生的瞬间立即增大,并在追逐期间呈现轻微下降趋势。脉冲间隔的增大对应着探测距离的增加,代表着海豚对未知区域的探索能力,制约着它的逃离速度。数据记录结果的分析表明,伊洛瓦底海豚会根据外界干扰对发出的回声定位信号进行调整,改变自己对潜在危险的探查能力。分析结果同时提醒我们需要随海豚生存环境的噪声进行管理,避免突然的发动机操作或者追逐它们。     

Effectiveness of zinc application to minimize cadmium toxicity and accumulation in wheat (Triticum aestivum L.)

Cadmium (Cd) is a highly toxic heavy metal and its presence in soil is of great concern due to the danger of its entry into the food chain. Among many others, proper plant nutrition is an economic and practicable strategy for minimizing the damage to plants from Cd and to decrease Cd accumulation in edible plant parts. The study was carried out to compare the effectiveness of soil and foliar applications of zinc (Zn) to minimize Cd accumulation in wheat grains. The results revealed that the exposure of plants to Cd decreased plant growth and increased Cd concentration in the shoots and grains of wheat, when compared with unexposed plants. Foliar application of 0.3 % zinc sulfate solution effectively decreased Cd concentration in wheat grains. Foliar application of Zn at a suitable concentration can effectively ameliorate the adverse effects of Cd exposure and decrease the grain Cd concentration of wheat grown in Cd-contaminated soil.     

Emission of scalar particles from cylindrical black holes

We study quantum tunneling of scalar particles from black strings. For this purpose we apply WKB approximation and Hamilton-Jacobi method to solve the Klein-Gordon equation for outgoing trajectories. We find the tunneling probability of outgoing charged and uncharged scalars from the event horizon of black strings, and hence the Hawking temperature for these black configurations.