32 research outputs found
Applications of queuing systems with correlated reneging
No full textProf Rakesh Kumar
Professor, Department of Mathematics and Statistics, NUS
ASSESSMENT OF PHYSICO-CHEMICAL PARAMETERS ON WATER QUALITY OF NARMADA GHATS,JABALPUR INDIA
No full textDr.Shailza Verma Prof. Rakesh Kumar Grover Chandrashekhar Pate
Simulation and flowsheeting of agro industrial residues torrefaction: the case of tomato peels waste
No full textTorrefaction is a thermal pretreatment for biomass feedstocks of various origin, which is usually carried out in an inert atmosphere, at ambient pressure and in a temperature range of 200-300 °C. It has the ability to reduce the main logistic and application limitations of biomass, arising from its heterogeneity, low bulk density, low energy density, hygroscopic behavior and fibrous nature. During torrefaction a combustible gas (‘torgas’) consisting of different organic compounds is also produced in addition to the torrefied solid product. In a properly designed and operated torrefaction system the torgas may be combusted to generate heat for the drying and torrefaction steps, thus increasing the overall process efficiency.
This paper focuses on the valorization of biomass made available from low-value, wet agro-industrial residues. The aim of this work is to provide the conceptual design and technical analysis of a torrefaction process for recovery and upgrade of wet tomato peels, which are a typical industrial waste in the Campania region (IT).
The Aspen PlusTM software was used to depict the flowsheeting of the investigated torrefaction process, to develop and solve material and energy balances of the whole process, to carry out the internal heat integration steps. A novel aspect is the modeling of the torrefaction reactor, which was carried out by taking advantage of experimental correlations available in the literature from authors’ previous work. Drying of the wet biomass feedstock results a very energy-demanding operation. The main output of this study is the calculation of the process energy demand from external sources. Therefore, the paper discusses how far the torrefaction process of high-moisture tomato peel residues is from autothermal operation, provided the best available process design options and internal heat integration steps
A Graphical User Interface for dynamics and feedback control studies focus on chemical reactors
No full textA program in MATLAB’s Graphical User Interface (GUI) is
developed to study dynamic behavior and traditional PID control
of simple nonlinear reference systems, such as a discontinuous
batch reactor and a continuous bioreactor. Once either system is
selected by the GUI user, the program underlying the GUI
provides simulation for various values of the input variables in an
easy and intuitive way, showing a strong educational value. It
allows exploration of simulation, modeling and control for users
without theoretical knowledge
Numerical Modeling and Optimization of Fractured Structures via Machine Learning and Topology Optimization
Get PDFDuring the continuous development of science and technol-
ogy, optimization plays a tremendous role in improving our
resources without compromising the quality of performance.
This thesis work investigates the application of the phase-
field method for fracture (PFF) in brittle materials, focusing
on the understanding of the influence of the model parame-
ters, both for the isotropic and the anisotropic cases, in cap-
turing the mechanical response of experimental results. For
the PFF isotropic case, an experimental investigation was car-
ried out on an ABS co-polymers. A MATLAB-based algo-
rithm combining particle swarm optimization (PSO) with PFF
has been utilized to determine optimal values of Young’s mod-
ulus (E), fracture toughness (Gc), and the PFF internal length
scale (lc) through uni-axial tensile and three-point bending
tests. To understand the potential of bio-polymers in vari-
ous industrial applications, 3D printed PLA materials were
fabricated via fusion deposition modeling, and due to their
anisotropic behavior, an anisotropic PFF approach was ex-
ploited. A metaheuristic machine learning algorithm coupled
with PFF demonstrates robustness in estimating fracture pa-
rameters (Gc, lc, β) and a strong influence of β the penalty
parameter on the predicted force-displacement curves.
The thesis examine also the critical issue of delamination at
internal interfaces/adhesive joints and internal cracks in com-
posite and multi-material components, which can lead to catas-
trophic failures. Existing structural topology optimization
(TO) methods typically assumes perfect bonding, which urges
the development of approaches that explicitly optimize struc-tures against delamination. The proposed data-driven heuris-
tic optimization strategy has been applied to identify optimal
cohesive interface properties with linear grading, enhancing
the composite structure’s resistance to peeling. Additionally,
it explored the application of the Solid Isotropic Material with
Penalty (SIMP) topology optimization approach to optimize
substrate internal structures affected by interface delamina-
tion.
The integration of a phase-field for fracture (PFF) approach
with TO has been highlighted as a robust mathematical frame-
work to mitigate crack progression in structures compromised
by initial damage under operational loads. Employing the
SIMP technique and optimality criteria (OC) method, the re-
search validated its effectiveness through numerical exam-
ples, demonstrating potential improvements in fracture re-
sistance for damaged structures crucial in aerospace, marine,
automotive, and civil engineering industries
Data Analysis in a Batch Salami Ripening Chamber for Real-Time Process Monitoring and Control
No full textThe paper provides an analytical and visual view of what actually happened - on the process side - in a fully instrumented, pilot-scale, air ascending-flow chamber of industrial type for salami ripening. Since ripening is always characterized by a "slow" dynamics and limited variations in process variables, the time course of the curing air temperature and humidity, as well as the sausage heart temperature, did not show rapid or incomprehensible transients. The monitored variables clearly showed limited amplitude oscillations due to the "go" and "stop" air circulation pattern, that is the sequence of phases with either forced or natural circulation in the cell as imposed by the supervision system for the automatic control of the chamber set points. The effectiveness of set point tracking was favorably assessed for the experimental tests. Then, comparisons were made between different measurements of the same variable, e.g., air temperature and humidity, monitored by probes at different heights in the chamber; similarly, the temperature measured by a TC at the heart of the sausage was matched to the curing air temperature in the chamber. From these comparisons and other crossed checks among data, it was possible to obtain static (e.g. the effect of the position on air temperature at equal height) and dynamic (e.g., the sausage temperature response to the temperature variations in the chamber) assessments of the process variables.
All in all, the work done and its further exploitation offer a tool set for a real-time aid to a factory operator
Effect of density stratification on dynamos in gas planets and low-mass stars
Get PDFNumerical simulations of the Geodynamo have reproduced many of the features of the Earth's magnetic field. An ensemble of these simulations has been used to formulate a predictive scaling law which agrees with the Earth's mean magnetic field strength. Surprisingly, this scaling law also predicts the field strength in Jupiter and some rapidly rotating stars whose convection-zones are drastically different from the one in Earth. The main aim of this thesis is to explore scaling laws in dynamos which incorporate ingredients suitable for convection-zones of gas-planets and low-mass stars, i.e. stress-free flow boundary conditions and compressible fluids. The resulting simulations indicate that despite drastic changes in the flow structure the scaling law relating the field strength to the flow-driving power is mostly unaffected, indicating that dynamos in rapidly-rotating planets and stars might behave similarly. We also use numerical simulations to investigate latitudinal differential rotation in planets and stars to provide a common framework, and the effect of various control parameters, initial condition, and magnetic field on its nature and vigour is also explored. Inspired by the idea that some planetary and stellar dynamos might belong to the same category I run dedicated high-resolution dynamo simulations of stellar dynamos. The control parameters for these simulations were such that an Earth like dipole-dominated magnetic field was produced. The resulting simulations spontaneously generate dark spot at high latitudes, providing a self-consistent mechanism for high-latitude starspot formation in rapidly rotating stars
A CRITICAL REVIEW ON THE MATERIAL ASPECTS OF TRIBOELECTRIC NANOGENERATORS (TENG)
Get PDFTriboelectric nanogenerators (TENG) take the advantage of coupling effect for harvesting energy in the area of electronics for various self-powered applications. These nanogenerators are capable of converting energy in our surroundings into electrical energy by using the process of electrostatic induction and contact electrification. Triboelectric layers of a TENG are formed basically with the use of various polymers, metals and other inorganic materials like PTFE (Poly tetra fluoro ethylene), PDMS (polydimethyl siloxane), FEP (Fluorinated ethylene propylene) and Kapton. Selection of different materials for the device fabrication is very important since it contribute towards the triboelectric effect and also forms the fundamental structure for the proposed TENG device. In this review article, we emphasis mainly on various triboelectric materials considering factors such as stability, flexibility, power density etc., to improve upon the electrical output of the devices for different applications
International Journal of Advances in Engineering Research NEW REGIME FOR THE SYNCHRONIZATION OF TIMINGS IN WIRELESS SENSOR NETWORK
Get PDFABSTRAC
Cost Optimization in Batch Industrial Salami Ripening through Mathematical Modeling
No full textWithin a recent research project (PON Safemeat) devoted to "innovative" fresh and fermented meat-based products, the project partners' chambers were used for salami ripening and a number of experimental tests were carried out under strictly controlled conditions. In addition to both process and product data obtained during ripening, the PON Safemeat has also allowed focusing on production cost data. Therefore, a mathematical model was developed to express costs associated to the industrial batch ripening of salami and an objective function was devised with the goal of optimization.
The model considers the cost of raw materials, the operating costs (linearly increasing with time during maturing) and, finally, a cost for the "loss of quality" of an off-specification product, expressed as a "non-revenue" and referred to as "QL factor". The objective function is a nonlinear function of the non-dimensional time t*.
Two test cases have been constructed by considering Italian traditional sausage products, i.e., the spicy "Soppressata A" produced by Dodaro SpA and the "Salame of Felino", and the corresponding results have been analyzed and compared. The outcome of this work is interesting at present and promising in the future for further development and validation activities
