Thermal Investigation on Coated and Uncoated HSS Twist Drill using ANSYS Software

In drilling, a cylindrical hole is produced in workpiece, removing the material inside the workpiece. The cutting tool used in drilling operation is called ‘Twist Drill’; it rotates and allows the material to be removed from the workpiece in the form of chips and thus drill the hole. Cutting fluids or coolants are used to perform this operation smoothly. The coating on the drill bits helps to reduce friction in the cut and the heat buildup in the drill bit. Coating also helps in protecting against corrosion. The present work focuses on the features of uncoated High Speed Steel (HSS) Twist Drill bit and Titanium Nitride (TiN) and Titanium Aluminium Nitride (TiAlN) coated on HSS Drills. The workpiece material was Mild Steel and the drilling operation was done using normal machining condition i.e. in presence of coolant. The cutting parameters used are cutting speed (35.5 m / min), spindle speed (1500 rpm), feed rate (0.2 mm / rev.), depth of cut (10 mm). These parameters were kept constant. Temperatures were measured with the help of thermal imaging camera and with the help of ANSYS software thermal analysis were done. Experimental results showed that the average rise in temperature of uncoated HSS tool was higher as compared to TiN coated and TiAlN coated HSS tools. TiAlN coated drills showed the least average rise in temperature. Keywords: High Speed Steel (HSS) Drill, TiN and TiAlN Coated HSS Twist Drill, Mild Steel (MS), Thermal Analysis, ANSYS Software.

Turbulence modulation in buoyancy-driven bubbly flows

We present a direct numerical simulation (DNS) study of buoyancy-driven bubbly flows in the presence of large-scale driving that generates turbulence. On increasing the turbulence intensity: (a) the bubble trajectories become more curved and (b) the average rise velocity of the bubbles decreases. We find that the energy spectrum of the flow shows a pseudo-turbulence scaling for length scales smaller than the bubble diameter and a Kolmogorov scaling for scales larger than the bubble diameter. We conduct a scale-by-scale energy budget analysis to understand the scaling behaviour observed in the spectrum. Although our bubbles are weakly buoyant, the statistical properties of our DNS are consistent with the experiments that investigate turbulence modulation by air bubbles in water.

Polar Amplification and Ice Free Conditions under 1.5, 2 and 3 °C of Global Warming as Simulated by CMIP5 and CMIP6 Models

One of the most visible signs of global warming is the fast change in the polar regions. The increase in Arctic temperatures, for instance, is almost twice as large as the global average in recent decades. This phenomenon is known as the Arctic Amplification and reflects several mutually supporting processes. An equivalent albeit less studied phenomenon occurs in Antarctica. Here, we used numerical climate simulations obtained from CMIP5 and CMIP6 to investigate the effects of +1.5, 2 and 3 °C warming thresholds for sea ice changes and polar amplification. Our results show robust patterns of near-surface air-temperature response to global warming at high latitudes. The year in which the average air temperatures brought from CMIP5 and CMIP6 models rises by 1.5 °C is 2024. An average rise of 2 °C (3 °C) global warming occurs in 2042 (2063). The equivalent warming at northern (southern) high latitudes under scenarios of 1.5 °C global warming is about 3 °C (1.8 °C). In scenarios of 3 °C global warming, the equivalent warming in the Arctic (Antarctica) is close to 7 °C (3.5 °C). Ice-free conditions are found in all warming thresholds for both the Arctic and Antarctica, especially from the year 2030 onwards.

From Mad Men to Maths Men: Concentration and Buyer Power in Online Advertising

This paper analyzes the impact of intermediary concentration on the allocation of revenue in online platforms. We study sponsored search documenting how advertisers increasingly bid through a handful of specialized intermediaries. This enhances automated bidding and data pooling, but lessens competition whenever the intermediary represents competing advertisers. Using data on nearly 40 million Google keyword auctions, we first apply machine learning algorithms to cluster keywords into thematic groups serving as relevant markets. Using an instrumental variable strategy, we estimate a decline in the platform’s revenue of approximately 11 percent due to the average rise in concentration associated with intermediary merger and acquisition activity. (JEL C45, D44, G34, L13, L81, M37)

The Effects of Salinity on the Anatomy and Gene Expression Patterns in Leaflets of Tomato cv. Micro-Tom

Salinity is a form of abiotic stress that impacts growth and development in several economically relevant crops and is a top-ranking threat to agriculture, considering the average rise in the sea level caused by global warming. Tomato is moderately sensitive to salinity and shows adaptive mechanisms to this abiotic stressor. A case study on the dwarf tomato model Micro-Tom is here presented in which the response to salt stress (NaCl 200 mM) was investigated to shed light on the changes occurring at the expression level in genes involved in cell wall-related processes, phenylpropanoid pathway, stress response, volatiles’ emission and secondary metabolites’ production. In particular, the response was analyzed by sampling older/younger leaflets positioned at different stem heights (top and bottom of the stem) and locations along the rachis (terminal and lateral) with the goal of identifying the most responsive one(s). Tomato plants cv. Micro-Tom responded to increasing concentrations of NaCl (0-100-200-400 mM) by reducing the leaf biomass, stem diameter and height. Microscopy revealed stronger effects on leaves sampled at the bottom and the expression analysis identified clusters of genes expressed preferentially in older or younger leaflets. Stress-related genes displayed a stronger induction in lateral leaflets sampled at the bottom. In conclusion, in tomato cv. Micro-Tom subjected to salt stress, the bottom leaflets showed stronger stress signs and response, while top leaflets were less impacted by the abiotic stressor and had an increased expression of cell wall-related genes involved in expansion.

Analysis of electrooculogram (EOG) signals in studying myasthenia gravis

Myasthenia Gravis (MG) is a neuromuscular disorder that induces muscle weakness and fatigue which can be fatal. A common precursor for severe form of MG is ocular MG. In this thesis, we explored signal processing methodologies for early stage detection of MG using electrooculogram (EOG) signals. An EOG signal database consisting of 62 control and 16 MG (mild to moderate) subjects were analyzed for eye movement characteristics and EOG signal morphologies using time domain and wavelet domain techniques. A linear discriminant analysis (LDA) based classifier was used to quantify the ability of features in separating MG from control samples. Average overall classification accuracy achieved by the proposed method for the best time domain feature (average rise rate) and best wavelet feature (scale band energy) was 82.5% (P<0.01, AUC=0.887) and 83.8% (P<0.01, AUC=0.893), respectively. The obtained results suggest EOG based analysis is a viable, non-invasive alternative MG screening method.

Analysis of electrooculogram (EOG) signals in studying myasthenia gravis

Myasthenia Gravis (MG) is a neuromuscular disorder that induces muscle weakness and fatigue which can be fatal. A common precursor for severe form of MG is ocular MG. In this thesis, we explored signal processing methodologies for early stage detection of MG using electrooculogram (EOG) signals. An EOG signal database consisting of 62 control and 16 MG (mild to moderate) subjects were analyzed for eye movement characteristics and EOG signal morphologies using time domain and wavelet domain techniques. A linear discriminant analysis (LDA) based classifier was used to quantify the ability of features in separating MG from control samples. Average overall classification accuracy achieved by the proposed method for the best time domain feature (average rise rate) and best wavelet feature (scale band energy) was 82.5% (P<0.01, AUC=0.887) and 83.8% (P<0.01, AUC=0.893), respectively. The obtained results suggest EOG based analysis is a viable, non-invasive alternative MG screening method.

Thermal Analysis of Solar Tunnel Dryer and Evaluation for Commercial Mango Leather Drying

A walk-in type semi-cylindrical-shaped solar tunnel dryer (10 m x 3.75 m) was designed, developed, and evaluated at Dr. B.S. Konakan Krishi Vidyapeeth, Dapoli for thermal analysis. The dryer was evaluated by conducting the no-load test at the laboratory to study the thermal profile, energy input/output during the winter and summer seasons. Based on the laboratory experience, a commercial-scale solar tunnel dryer was installed and evaluated at M/s Shirodkar Food Products Pvt. Ltd., kudal, District Sindhudurg (MS) for commercial mango leather drying. The dryer was loaded with 250 kg mango pulp per batch by spreading over 210 number of grease-proof aluminum trays (1.2 kg pulp in each tray) in three layers (70 trays in each layer). Drying of mango leather was studied in comparison with open sun drying and electrical oven drying for time saving and energy consumption. The study revealed that the average rise in temperature of drying air was about 18 -22 0C over the ambient air. The average drying period reduced by 28 % over open sun drying method. The average temperature inside the solar dryer was 62+5 0C, and required 10 h for upper layer of trays, 13 h for second layer of trays, and 17 h for the third level of trays as compared to 26 h in open sun drying. The operating energy cost of solar tunnel dryer was zero as compared to 102 kWh in an electrical oven. Considering drying of 30 batches per season, the payback period of the system was 2.7 years

Last Chance Tourism in South Africa

Last Chance Tourism (LCT) is defined by tourists’ urgent visits to landscapes and seascapes, natural environments and places of social and cultural importance/heritage before they disappear. The obliteration of these environments is attributed to the rapid and destructive effects of global environmental change and globalization. These influences are leading to the demise of natural systems and biodiversity, including in polar regions and coral reef systems. Furthermore, cultures and traditions are also being lost. Scholarly investigations to date have reflected on the contention between the experiential gain in visiting destinations before they disappear on the one hand, and the losses to, and demise of, those very destinations through such visits. Despite above-global-average rise in temperature, increasingly frequent droughts and flooding, as well as rapid globalization, the South African experience on LCT destinations remains under-investigated. This paper uses secondary sources to explore current and future destinations where cultural groups are threatened, fauna and flora are on the brink of extinction, and landscapes are changing for the worse. Future research opportunities are identified and conceptual concerns are discussed.

Quality of soy bean grain stored in bag silo

Because of the rise in the use of bag silo in the last harvests due to the lack of static capacity in Brazil, the storage of grain in type of structure is currently seen as a solution to our storage deficit. Thus, the importance of maintaining the quality of grains for commercialization in these systems is considered. The objective of this experiment was to evaluate the quality of soybean grain stored in a silo bag, in the region of Dourados, State of Mato Grosso do Sul, Brazilian Central-West. The experiment was carried out in a cooperative, where soybean grain stored in silo bag are collected. The product had been received, processed at the end of the summer harvest and previously stored in metallic silos, and then transferred to the silo bags upon reception of the winter harvest. Thus, soybeans with an average water content of 11% w.b. were packed in bags composed of high-density polyethylene and hermetically sealed over a total period of 125 days, with collections of data on temperature and air relative humidity and grain sampling every 40 days. The collected samples were subjected to plant classification and analyses of water content, water activity, protein, lipids and color parameters were also performed. Na average rise of 5° C was observed in the temperature and 14% for air relative humidity which resulted in the of moldy and fermented grains after 125 days in the bags. The storage period factor was significant (p <0.05) in the variables of water content, color and oil. It was concluded that for soybeans the storage period in hermetic bags influences the quality of the grains and the internal environmental conditions in these structures are influenced by the convective microcurrents observed in the different positions inside the silo bag.