Robust Model Predictive Control for Signal Temporal Logic Synthesis

Most automated systems operate in uncertain or adversarial conditions, and have to be capable of reliably reacting to changes in the environment. The focus of this paper is on automatically synthesizing reactive controllers for cyber-physical systems subject to signal temporal logic (STL) specifications. We build on recent work that encodes STL specifications as mixed integer linear constraints on the variables of a discrete-time model of the system and environment dynamics. To obtain a reactive controller, we present solutions to the worst-case model predictive control (MPC) problem using a suite of mixed integer linear programming techniques. We demonstrate the comparative effectiveness of several existing worst-case MPC techniques, when applied to the problem of control subject to temporal logic specifications; our empirical results emphasize the need to develop specialized solutions for this domain

Effect of Alternate Metals for use in Natural Fibre Reinforced Fibre Metal Laminates under Bending, Impact and Axial Loadings

AbstractFibre Metal Laminate (FML) is largely used in the manufacture of aircrafts. The commercially available FMLs, GLARE, CARALL (CArbon Reinforced ALuminium Laminate) and ARALL make use of Aluminium metal. Other FMLs that are under study by researchers make use of metals such as Titanium and Magnesium based alloys. Owing to the high cost of carbon fibre and the necessity for environment friendly alternatives, in the present work, a portion of carbon is replaced by natural fibre jute in CARALL and CARMAL (CArbon Reinforced MAgnesium Laminate). To the knowledge of the authors, this attempt has not been made before in the field of FMLs. The resulting CArbon-Jute Reinforced ALuminium Laminate and CArbon-Jute Reinforced MAgnesium Laminate are named as CAJRALL and CAJRMAL. Both these laminates are made by hand layup technique and then compressed in a compression moulding machine. The CAJRALL and the CAJRMAL specimens are subjected to Axial, Flexure and Impact tests according to ASTM standards. The effect of the orientations of fibres and influence of the stacking sequences of the fibre and metal combinations and the use of alternating metals on the mechanical performance, are experimentally investigated. The experimental and theoretical results as well as the results obtained through Finite Element Analysis are found to be in close agreement. Also the failure of the FML is predicted by conducting micro level structure analysis

Robust Model Predictive Control for Signal Temporal Logic Synthesis

Most automated systems operate in uncertain or adversarial conditions, and have to be capable of reliably reacting to changes in the environment. The focus of this paper is on automatically synthesizing reactive controllers for cyber-physical systems subject to signal temporal logic (STL) specifications. We build on recent work that encodes STL specifications as mixed integer linear constraints on the variables of a discrete-time model of the system and environment dynamics. To obtain a reactive controller, we present solutions to the worst-case model predictive control (MPC) problem using a suite of mixed integer linear programming techniques. We demonstrate the comparative effectiveness of several existing worst-case MPC techniques, when applied to the problem of control subject to temporal logic specifications; our empirical results emphasize the need to develop specialized solutions for this domain

Model Predictive Control for Signal Temporal Logic Specification

We present a mathematical programming-based method for model predictive control of cyber-physical systems subject to signal temporal logic (STL) specifications. We describe the use of STL to specify a wide range of properties of these systems, including safety, response and bounded liveness. For synthesis, we encode STL specifications as mixed integer-linear constraints on the system variables in the optimization problem at each step of a receding horizon control framework. We prove correctness of our algorithms, and present experimental results for controller synthesis for building energy and climate control

Online Horizon Selection in Receding Horizon Temporal Logic Planning

Temporal logics have proven effective for correct-by-construction synthesis of controllers for a wide range of applications. Receding horizon frameworks mitigate the computational intractability of reactive synthesis for temporal logic, but have thus far been limited by pursuing a single sequence of short horizon problems to the current goal. We propose a receding horizon algorithm for reactive synthesis that automatically determines a path to the currently pursued goal at runtime, in response to a nondeterministic environment. This is achieved by allowing each short horizon to have multiple local goals, and determining which local goal to pursue based on the current global goal, currently perceived environment and a pre-computed invariant dependent on each global goal. We demonstrate the utility of this additional flexibility in grant-response tasks, using a search-and-rescue example. Moreover, we show that these goal-dependent invariants mitigate the conservativeness of the receding horizon approach

Beneficiation studies on beach placer sample for steel making industries

Beneficiation studies were carried out on the Talashil beach placer sample of South Maharastra Coast, India. The sample contains magnetite, ilmenite, rutile, hematite, goethite and chromite as opaque minerals in the sample. The total heavy minerals fraction reaches 53.8 % by weight whereas the total magnetic minerals are 56.9%. It is observed that the 2nd stage DHIMS magnetic fraction contains 65.2 % Fe2O3 with an over all yield of 37.8 % and a 86 % recovery from a containing 26.8 % Fe2O3 feed. This product can be used in the pellet feed for steel making after suitable blending with high-grade iron ore fines

Extraction and Flotation Performance Evaluation of Bio-collector in High Ash Graphite Ore Beneficiation

The rapid depletion of high-grade ores and natural resources, utilization of low-grade ores by beneficiation becomes utmost importance for sustainable development and resource management. The increasing wide range of applications of graphite for electrode, lubricants, refractory applications especially the recent surging electric automobile industry, resulting in significant need of graphite in future. Graphite demand in the energy storage industry is expected to grow faster than today's demand in future. Most of the graphite ore deposits in India are of low grade containing high ash content. Graphite is a naturally hydrophobic mineral and froth flotation process involves separation of minerals based on its surface hydrophobicity. The chemical reagents commonly used in graphite flotation are hydrocarbon oils such as diesel, kerosene along with a frothing agent such as methyl isobutyl carbinol (MIBC) which are non-environment friendly, hazardous and not cost effective while used at large scale industrial processing of the ore. Hence, in this work, a new eco-friendly bio-collector was developed from the exocarp or rind of a shrubaceous plant as an alternate flotation reagent for graphite. The flotation performance efficacy of this bio-collector was evaluated in comparison to the existing practice of diesel-MIBC dual reagent system in graphite flotation. A high ash low-grade graphite ore from eastern India with 84.71% ash and 9.07% fixed carbon was beneficiated by flotation technique for recovering graphite with lower ash content. The ore characterization studies mineralogy (XRD, ore microscopy) and morphology (SEM) reveal that the graphite mineral phase with sheet like appearance was accompanied predominantly by quartz, with minor fractions of biotite, muscovite and kaolinite. The spectral analysis of the developed bio-collector was characterized (FTIR). Under similar flotation test conditions on processing the high ash graphite ore, a final concentrate graphite product with 11.40% ash using diesel & MIBC as flotation reagents and 11.74% ash using bio-collector was obtained which indicates that the developed bio-collector could be a potential replacement for diesel- MIBC reagents being used in graphite processing mineral industries. Also, this bio-collector has an added advantage of being a natural plant-based extract with environmental compatibility leading to a step towards clean ore processing

Base pair opening and bubble transport in a DNA double helix induced by a protein molecule in a viscous medium

We study the nonlinear dynamics of a protein-DNA molecular system by treating DNA as a set of two coupled linear chains and protein in the form of a single linear chain sliding along the DNA at the physiological temperature in a viscous medium. The nonlinear dynamics of the above molecular system in general is governed by a perturbed nonlinear Schr\"{o}dinger equation. In the non-viscous limit, the equation reduces to the completely integrable nonlinear Schr\"{o}dinger (NLS) equation which admits N-soliton solutions. The soliton excitations of the DNA bases make localized base pair opening and travel along the DNA chain in the form of a bubble. This may represent the bubble generated during the transcription process when an RNA-polymerase binds to a promoter site in the DNA double helical chain. The perturbed NLS equation is solved using a perturbation theory by treating the viscous effect due to surrounding as a weak perturbation and the results show that the viscosity of the solvent in the surrounding damps out the amplitude of the soliton.Comment: 4. Submitted to Phys. Rev.

Flotation of low-grade graphite ore using collector derived from low density polyethylene waste

The increasing wide range of applications of graphite for electrode, lubricants, refractory applications especially the recent surging electric automobile industry, resulting in significant need of graphite in future. Graphite demand in the energy storage industry is expected to grow 15 times faster than today's demand by 2030. Due to depleting high-grade ore, utilization of low-grade ore by beneficiation becomes utmost importance for sustainable development and resource management. In this work, low-grade graphite ore from Tamil Nadu, India with 86.84% ash was beneficiated by flotation technique for recovering graphite with lower ash content. Flotation, a surface phenomena, based on the surface hydrophobicity of the mineral surface to be separated and since graphite is naturally flotation mineral, this technique is adopted for beneficiation. The mostly commonly used collector in graphite flotation is diesel. In view of continuous cost escalation of diesel, an alternate collector was developed utilizing the low-density polyethylene (LDPE) waste paving way for plastic waste utilization. The flotation efficacy of this new collector (Collector PE) derived from LDPE waste was compared with that of diesel in graphite flotation. The run-of mine graphite ore was initially size reduced for liberation of values from its associated impurities, followed by flotation. The mesh-of-grind, dosages of collector (diesel and PE) and frother (Methyl Isobutyl Carbinol, MIBC) were optimized for better process efficiency for increasing the surface hydrophobicity of graphite particles leading to better separation efficacy. The ore characterization by x-ray diffraction revealed that graphite was accompanied predominantly by quartz with minor fractions of pyrites and several other phyllosilicates such as kaolinite and muscovite. Exfoliated morphology of graphite with thick layers were observed from SEM images. Flotation reagents such as diesel, collector PE and MIBC were characterized by FTIR to analyze their functional groups that enhances the efficiency of the separation process. A graphite float (rougher concentrate) with 15.2% weight recovery and 17.7% ash content was obtained after 10 minutes of grinding (d80: 240.5µm) with 0.85kg/t of collector (diesel) and 0.07kg/t of frother (MIBC) dosages and on two-stage cleaning, a final concentrate with 12.66% weight recovery and 8.70% ash content was obtained. A graphite final concentrate with 13.04% weight recovery and 8.90 % ash was achieved with two-stage cleaning, when treated with 0.57 kg/t of collector PE and 0.07 kg/t of MIBC. These results indicate that the flotation efficiency of the collector PE derived from LDPE wastes is comparable with that of diesel and would be economical when used in large scale industrial graphite flotation

Compressive Behaviour of RC Column with Fibre Reinforced Concrete Confined by CFRP Strips

The structural application of synthetic fibre reinforced concrete (FRC) has become widespread in the construction industry in order to satisfy the requirement of the earthquake resistant structures. Research conducted so far are focused on the structural behaviour of RC column externally confined with FRP composites, while studies are needed to address the behaviour of FRP strengthened RC column fabricated using fibre reinforced concrete. With the intention that the experimental investigation was carried out to evaluate the feasibility use of CFRP composite strips in strengthening of RC column made with fibre reinforced concrete. Circular synthetic Polypropylene fibre was used in the rate of 0.50% in the volume of concrete. CFRP strips having a width of 50 mm were used to confine the column and the experimental parameters were effective spacing between the CFRP strips (20 mm and 30 mm) and the number of CFRP layers (one, two and three). The externally bonded CFRP strips counteract the lateral expansion of the concrete significantly by providing restraining effect and thus effect enhanced the stiffness of the column. The column strengthened with CFRP strips showed a maximum of 198.87% and 91.75% enhancement in axial deformation control and ultimate strength, respectively, compared to that of reference column. From the test results obtained, it is suggested that CFRP strips with the spacing of 20 mm and 30 mm can be used in strengthening of RC column made with FRC; however the column confined with 30 mm spacing provides an economical advantage compared to that of 20 mm spacing