Jadavpur University

About: Jadavpur University is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Population & Schiff base. The organization has 10856 authors who have published 27678 publications receiving 422069 citations. The organization is also known as: JU & Jadabpur University.

The potential of cropping systems and soil amendments for carbon sequestration in soils under long‐term experiments in subtropical India

Abstract: An understanding of the dynamics of carbon (C) stock in soils, as impacted by management strategies, is necessary to identify the pathways of C sequestration in soils and for maintaining soil organic C (SOC) at a level critical for upkeeping soil health and also for restraining global warming. This is more important in tropical and subtropical region where soils are inherently low in organic C content and the production system is fragile. We evaluated the long-term role of crop residue C inputs to soil in SOC sequestration and also the critical value of C inputs for maintenance of SOC across five different rice-based cropping systems and four soil management practices including a fallow (no cultivation since initiation of the experiments) using five long-term (7–36 years) fertility experiments in subtropical India. Cropping per se always caused a net depletion of SOC. Such depletion was inversely proportional to the amount of crop residue C incorporated into the soils (r=−0.92, P=0.001). Balanced fertilization with NPK, however, caused an enrichment (9.3–51.8% over the control) of SOC, its extent being influenced by the cropping systems. Long-term application of organic amendments (5–10 Mg ha−1 yr−1) through farmyard manure (FYM) or compost could increase SOC hardly by 10.7% constituting only 18% of the applied C, the rest getting lost through oxidation. The total quantity of soil C sequestered varied from −11.5 to 14.5 Mg C ha−1 and was linearly related (r2=0.40, P=0.005) with cumulative crop residue C inputs to the soils. On an average, the rate of its conversion to SOC came out to be 6.4%. This was more in presence of added organics (6.9%) than in its absence (4.2%). For sustenance of SOC level (zero change due to cropping) we found that a minimum quantity of 2.9 Mg C is required to be added per hectare per annum as inputs. The cropping systems and the management practices that could provide C input higher than the above critical level are likely to sustain the SOC level and maintain good soil health in the subtropical regions of the Indian subcontinent.

Advancement in electrochemical micro-machining

Abstract: Electrochemical micro-machining (EMM) appears to be very promising as a future micro-machining technique, since in many areas of applications it offers several advantages, which include higher machining rate, better precision and control, and a wide range of materials that can be machined. In this paper, a review is presented on current research, development and industrial practice in micro-ECM. This paper highlights the influence of various predominant factors of EMM such as controlled material removal, machining accuracy, power supply, design and development of microtool, role of inter-electrode gap and electrolyte, etc. EMM can be effectively used for high precision machining operations, that is, for accuracies of the order of ±1 μm on 50 μm. Some industrial applications of EMM have also been reported. Further research into EMM will open up many challenging opportunities of improvement towards greater machining accuracy, new materials machining and generation of complex shapes for effective utilization of ECM in the micro-machining domain.

1.6 Ga U-Pb zircon age for the Chorhat Sandstone, lower Vindhyan, India: Possible implications for early evolution of animals

Abstract: Bedding-plane markings in the Chorhat Sandstone (lower Vindhyan), central India, were recently interpreted as burrows produced by triploblastic animals. Because the rocks were thought to be older than 1000 Ma, these structures were regarded as the oldest fossil evidence for metazoan life. However, the biological origin of the markings has been questioned, as has their age. Current age estimates are based on K-Ar, Rb-Sr, and fission- track dates, though some contentious evidence suggests that the rocks may be only 540 Ma. Here we provide the first robust age data for the lower Vindhyan by using SHRIMP (sensitive, high-resolution ion microprobe) U-Pb zircon geochronology to date silicified tuffs bounding the Chorhat Sandstone. Our results show that the sediments were deposited between 1628 ± 8 Ma and 1599 ± 8 Ma. If the Chorhat markings are burrows left by worm-like animals, then our data suggest that complex metazoans had evolved before 1600 Ma, 1 b.y. before the “Cambrian explosion” when animals rapidly diversified and became ecologically dominant. However, given the doubts expressed about the origin of the bedding-plane structures, as well as the surprisingly “old” age of the host rocks, further studies are urgently required to provide supportive evidence.

On the selection of tuning methodology of FOPID controllers for the control of higher order processes.

Abstract: In this paper, a comparative study is done on the time and frequency domain tuning strategies for fractional order (FO) PID controllers to handle higher order processes. A new fractional order template for reduced parameter modelling of stable minimum/non-minimum phase higher order processes is introduced and its advantage in frequency domain tuning of FOPID controllers is also presented. The time domain optimal tuning of FOPID controllers have also been carried out to handle these higher order processes by performing optimization with various integral performance indices. The paper highlights on the practical control system implementation issues like flexibility of online autotuning, reduced control signal and actuator size, capability of measurement noise filtration, load disturbance suppression, robustness against parameter uncertainties etc. in light of the above tuning methodologies.

Application of biogeography-based optimisation to solve different optimal power flow problems

Abstract: This study presents a biogeography-based optimisation (BBO) algorithm to solve optimal power flow (OPF) problems of a power system with generators that may have either convex or non-convex fuel cost characteristics. Different operational constraints, such as generator capacity limits, power balance constraints, line flow and bus voltages limits and so on, have been considered. Settings of transformer tap ratio and reactive power compensating devices have also been included as the control variables in the problem formulation. Biogeography describes how a species arises, migrates from one habitat to another and eventually gets wiped out. The algorithm developed using this concept is known as BBO, which searches for the global optimum mainly through two steps: migration and mutation. BBO has been implemented for three different objectives that reflect fuel cost minimisation, voltage profile and voltage stability improvement with the OPF embedded on IEEE 30-bus system. The superiority of the proposed method over other methods has been demonstrated for these three different objectives. Considering the quality of the solution obtained by the proposed method seems to be a promising alternative approach for solving the OPF problems.