bluuebunny/crossref_metadata_2025 huggingface dataset:
Wuchereria bancrofti macrophage migration inhibitory factor‐2 (rWbaMIF‐2) ameliorates experimental colitis
Authors: Ramani Shriram , Chauhan Nikhil , Khatri Vishal , Vitali Connie , Kalyanasundaram Ramaswamy
Published: January 2020

Immunomodulatory molecules produced by helminth parasites are receiving much attention recently as novel therapeutic agents for inflammation and autoimmune diseases. In this study, we show that macrophage migration inhibitory factor (MIF) homologue from the filarial parasite, Wuchereria bancrofti (rWbaMIF‐2), can suppress inflammation in a dextran sulphate sodium salt (DSS)‐induced colitis model. The disease activity index (DAI) in DSS given mice showed loss of body weight and bloody diarrhoea. At autopsy, colon of these mice showed severe inflammation and reduced length. Administration of rWbaMIF‐2 significantly reduced the DAI in DSS‐induced colitis mice. rWbaMIF‐2‐treated mice had no blood in the stools, and their colon length was similar to the normal colon with minimal inflammation and histological changes. Pro‐inflammatory cytokine genes (TNF‐α, IL‐6, IFN‐γ, IL‐1β, IL‐17A and NOS2) were downregulated in the colon tissue and peritoneal macrophages of rWbaMIF‐2‐treated mice. However, there were significant increases in IL‐10‐producing Treg and B1 cells in the colon and peritoneal cavity of rWbaMIF‐2‐treated mice. These findings suggested that rWbaMIF‐2 treatment significantly ameliorated the clinical symptoms, inflammation and colon pathology in DSS given mice. This immunomodulatory effect of rWbaMIF‐2 appeared to be by promoting the infiltration of Treg cells into the colon.
Integrating Concerns with Climate Change into Local Development Planning in Cambodia
Authors: Dany Va , Lebel Louis
Published: January 2020

Integration of climate change adaptation with development planning at multiple scales is widely seen as preferable to reactive, fragmented, or highly centralized responses. At the same time, there are growing concerns on when intervention is most appropriate, the transaction costs of coordination, and the adequacy of institutional capacity at local levels, especially in developing countries. This article examines entry points and mechanisms for integrating concerns with climate change into local development planning in Cambodia. An institutional ethnography of the planning process indicates that subnational planning is participatory and flexible; and thus, provides plausible entry points to integrate climate change concerns. Case study methods applied to two externally supported, climate‐resilient development projects identify promising mechanisms and strategies, as well as obstacles to integration. A vulnerability reduction assessment tool and top‐up grant scheme both included promising deliberative and participatory elements from which lessons for future and elsewhere can be drawn. At the same time, key stakeholders concede that local integration more widely is hampered by multiple obstacles, including weak institutional capacity, low community participation, and lack of resources and incentives. Addressing these challenges requires political commitments for good governance, capacity development, and additional resources.
Rent‐seeking, R&D, and productivity
Authors: Lai Yu‐Bong
Published: January 2020

To investigate whether rent‐seeking discourages productivity, we consider a third‐market model, in which a domestic firm and a foreign firm engage in both Research and Development (R&D) and output competition. We show that the relationship between rent‐seeking and productivity depends on two forces. On the one hand, rent‐seeking increases the marginal benefit of R&D and encourages productivity. On the other hand, a lower production cost due to R&D enables the government to extract the rent from the firm to a greater extent and discourages the productivity. Which force is dominant depends on the level of corruption or, as an alternative interpretation, the weight the government attaches to political contributions. Unlike the monotonic relationship proposed by the literature, we find a non‐monotonic relationship between rent‐seeking and productivity.
Effect of high nucleated cell concentration on product viability and hematopoietic recovery in autologous transplantation
Authors: Lin David Ming‐Hung , Hiskey Matthew , Huang Jane , Nickerson Cherie , Saisitthidej Desmond , Bradford Andrea , Woodburn Joshua , Lius Andrea , Skrzekut Adam , Tran Ellen , Haley Rebecca
Published: January 2020

BACKGROUND

Administering lower total product volumes with high nucleated cell (NC) concentrations may have the potential benefit of decreasing volume‐ and dimethyl sulfoxide (DMSO)‐related patient complications, while maximizing the laboratoryʼs freezer storage capacity. Our study is a retrospective investigation of the effect of HPC(A) products with cell concentrations greater than 3 × 108 NC/mL on clinical and product outcomes in patients undergoing autologous peripheral blood stem cell (PBSC) transplantation.

STUDY DESIGN AND METHODS

A total of 113 consecutive patients with hematological malignancies who underwent autologous PBSC transplantation were included in this retrospective analysis. The primary outcomes were days to initial absolute neutrophil count (ANC) recovery and initial platelet recovery. The secondary outcomes included the storage duration, segment thaw viability, and dose of viable CD34+ cells/kg administered.

RESULTS

Of 92 patients and 176 apheresis procedures, 81 patients received HPC(A) products with high NC concentration (4.1 × 108 NC/mL), and 11 patients received low NC concentration products (2.4 × 108 NC/mL). There were no observed differences in clinical outcomes with respect to ANC recovery (14 vs. 14 vs. 12 days) and platelet recovery (16 vs. 16 vs. 15 days) when very high NC (5.2 × 108 NC/mL) and high NC (4.1 × 108 NC/mL) groups were compared to the low NC group (2.4 × 108 NC/mL).

CONCLUSION

Our retrospective investigation provides further supporting evidence that HPC(A) products with cell concentration greater than 3 × 108 NC/mL did not show detrimental effects on the clinical outcomes in patients undergoing autologous PBSC transplantation.
Preliminary Design of an All-Ceramic Discrete-Structure Particle Heating Receiver
Authors: Peters George , Golob Matthew , Nguyen Clayton , Jeter Sheldon , Danish Syed , Elleathy Abdelrahman , Al-Ansary Hany
Published: January 2020

Discrete structure particle heating receivers (DS-PHR), as used in concentrated solar power (CSP) systems, employ suitable discrete porous structures to intermittently halt the falling particles to control the speed and increase the residence time of falling particulates, thereby increasing the temperature rise of particulates exiting the DS-PHR. Previous designs of DS-PHRs have considered both porous foam structures, which have mass flux limits, and metal wire meshes, which are effective but have temperature and other functional limitations. This paper recounts recent studies at Georgia Tech and King Saud University that have investigated the use of ceramic tiles made porous by discrete slot-shaped passages in place of previous metal wire meshes. Currently, for experimental use, the slot-like passages are cut into the tiles by water jet, but operational units are expected to be formed into shape and fired by more economical conventional ceramic techniques. Benefits of ceramic and other refractory materials include higher temperature and heat flux limits at a reasonable cost. The tiles are expected to be installed in chevron configuration, which have been shown by experience to be especially effective, and these so-called ceramic chevrons have been shown to deliver adequate mass flux densities while still removing most of the kinetic energy from the particles. In addition, the thickness of the tile allows the incorporation of angled slots capable of redirecting the particle flow, adding a method to control particle mixing by purposefully directing the particulate streams. These enhanced slots are typically arranged with adequate spacing to allow for increased penetration of concentrated light into the depth of the falling bed of particles and may be angled to redirect hot particles toward the back plane of the DS-PHR. Both of these features should help minimize depthwise temperature variation. The testing reported here will focus on the degree of velocity and flow control that can be achieved by proper design of these ceramic chevrons as well as demonstrate the effectiveness of different designs on light penetration. Prior to this research, the effectiveness of ceramic obstructions might have been properly doubted because of the very high coefficient of restitution (COR) for the impact of ceramic particles on ceramic solids. In reality, it will be shown that a layer of particulates will form on a chevron, which effectively dissipates the kinetic energy of the impacting particles. Overall, this paper will report improvements in DS-PHR designs that can withstand high temperatures and fluxes, achieve additional control of particle flow, enhance particle mixing, and allow deeper penetration of light into the depth of the falling bed.
A Real-Time C3 Continuous Tool Path Smoothing and Interpolation Algorithm for Five-Axis Machine Tools
Authors: Hu Qin , Chen Youping , Jin Xiaoliang , Yang Jixiang
Published: January 2020

Local corner smoothing method is commonly adopted to smooth linear (G01) tool path segments in computer numerical control (CNC) machining to realize continuous motion at transition corners. However, because of the highly non-linear relation between the arc-length and the spline parameter, and the challenge to synchronize the tool tip position and tool orientation, real-time and high-order continuous five-axis tool path smoothing and interpolation algorithms have not been well studied. This paper proposes a real-time C3 continuous corner smoothing and interpolation algorithm for five-axis machine tools. The transition corners of the tool tip position and tool orientation are analytically smoothed in the workpiece coordinate system (WCS) and the machine coordinate system (MCS) by C3 continuous PH splines, respectively. The maximum deviation errors of the smoothed tool tip position and the tool orientation are both constrained in the WCS. An analytical synchronization algorithm is developed to guarantee the motion variance of the smoothed tool orientation related to the tool tip displacement is also C3 continuous. The corresponding real-time interpolation method is developed with a continuous and peak-constrained jerk. Simulation results verify that the maximum deviation errors caused by the tool path smoothing algorithm are constrained, and continuous acceleration and jerk of each axis are achieved along the entire tool path. Comparisons demonstrate that the proposed algorithms achieve lower amplitude and variance of acceleration and jerk when compared with existing methods. Experiments show that the proposed five-axis corner smoothing and interpolation algorithms are serially executed in real-time with 0.5-ms cycle.
Conductivity and Electrochemical Behavior of Plasticized Polymer Electrolyte for Dye-Sensitized Solar Cell Integrated Supercapacitor
Authors: Poojari Vidyashri , Devadiga Dheeraj , Hegde Niveditha , Sangeetha D. N. , Santosh M. S. , Selvakumar M.
Published: January 2020

The current energy situation requires not only enormous energy in a brief period of time but clean energy as well. In this direction, a dye-sensitized solar cell (DSSC)—supercapacitor (SC) integrated energy device has been fabricated. This embedded energy system has a specific advantage such as easy manufacturing, low manufacturing costs, and flexible substrates compatibility. A natural photosensitizer was extracted from readily available beetroots and characterized using ultraviolet (UV)-visible spectroscopy. The zinc oxide semiconductor was synthesized using microwave technique and regarded as the DSSC photoanode material. The ZnO’s phase, purity, and morphology were investigated using X-ray diffraction (XRD) spectroscopy and scanning electron microscope. The iodine-doped cellulose acetate propionate (CAP) biopolymer electrolyte functions as the DSSC and supercapacitor electrolyte. The solid polymer electrolyte conductivity and dielectric studies were performed using electrochemical impedance spectroscopy (EIS). The laser-induced technique was used to synthesize graphene that plays a dual purpose as photocathode in DSSC and supercapacitor electrodes. The embedded energy unit from the DSSC-supercapacitor demonstrates a 6.75% fill factor representing its decent efficiency.
Development of Film Cooled Thruster for Rocket Application
Authors: Kumar Avanish , Venkateswarlu V. , Satyaprasad P. , Rao M. Raghavendra
Published: January 2020

An experimental investigation has been carried out for small liquid bi-propellant thrusters of 490 & 1500 N levels. These thrusters have to operate for more than 100 sec in continuous and pulse mode. In this case, film cooling is the primary mode of thruster cooling. The thruster uses hydrazine based propellant as fuel and N2O4 as oxidiser. Film cooling is carried out by injecting a fraction of fuel from an injector periphery. Unlike impinging type injection elements are used for core flow. The thruster’s shell used for testing was made of stainless steel and di-silicide coated C103 material. A 1D heat transfer model was developed for predicting the thruster outer wall temperature. The experimental investigation was carried for different film cooling percentage and injector configuration was modified for each case. Thermocouples were mounted on top & bottom side of shell for temperature measurement. Infrared camera also used for recording temperature in the test. Based on experimental investigation, effective film cooling percentage for optimum thruster performance has been estimated for two thrust levels and these studies also helped in validating the heat transfer model.
Potential Applications of Fuel Cells for Hybrid Electric Aircrafts: Case Study
Authors: Kari Sreedhar , Thorne George , Szeki John , Hall Chris , Mortimer Lindsey , Gerbeth Robby
Published: January 2020

Increased greenhouse gas emissions have an adverse impact on climate change. Recently, there is an increased drive to reduce the emissions especially after the Paris agreement 2015. There are several research initiatives that have been started in the aerospace industry to reduce the emissions like NOx, CO2 and other harmful substances. This paper presents the case studies done on the potential applications of fuel cells for more electric aircrafts (MEA) to achieve the reduced emissions and reduced fuel consumption. The objective of this paper is to take a broad view of how fuel cell technology works, various types of existing technologies and their potential applications and challenges for aero engines in terms of power density.

In this study, the different types of fuel cells e.g. low temperature Proton Exchange Membrane (PEM) fuel cells and high temperature solid oxide fuel cells (SOFC) etc were studied and identified the opportunities and challenges to make them work for aero engines as a part of electrification. Different ways of storing the hydrogen on board have been explored. The comparison has been made with battery vs fuel cell power density including the H2 tank. The case studies were made for potential replacement of shaft power off take on civil large engines with fuel cells for hybrid long range aircrafts and regional propeller jets with fully electric power.
Savonius Wind Turbine Blade Profile Optimization by Coupling CFD Simulations With Simplex Search Technique
Authors: Agrawal Ankit , Kansagara Divyeshkumar D. , Sharma Deepak , Saha Ujjwal K.
Published: January 2020

The Savonius rotor, a drag-based vertical axis wind turbine, is characterized by its design simplicity, low noise level, self-starting ability at low wind speed and low cost. However, its low performance is always a major issue. One of the remedies of this issue is to design an optimized rotor blade profile, which has mostly been developed through trial and error approach in the literature. In this paper, an optimum blade profile is obtained by maximizing its power coefficient (CP) by coupling CFD simulations of a rotor blade profile with the simplex search technique. Since the blade profile is symmetric about its axis, half of the blade geometry is created through natural cubic spline curve using three points. Two of them are kept fixed, whereas the other one is changed through optimization technique in its every iteration using MATLAB platform. In every iteration, the blade profile is meshed using ANSYS ICEM CFD. The analysis of the blade profile is performed through ANSYS Fluent by using shear-stress transport k-ω turbulence model. A finite volume method based solver is used to solve the transient 2D flow around the wind turbine. The optimum profile of the blade is compared with the conventional profile over a wide range of tip speed ratios (TSRs) in order to check its feasibility for practical applications. The optimum blade profile is found to be better than the semicircular blade in the range of TSR = 0.6–1.
Control of Lean Blowout in Partially Premixed Swirl-Stabilized Combustor Using a Fuel Rich Central Pilot Configuration
Authors: De Somnath , Mondal Prasanna , Sardar Gourav Manohar , Bokhtiar Rakin Bin , Bhattacharya Arijit , Mukhopadhyay Achintya , Sen Swarnendu
Published: January 2020

The main problem for using reliable and stable diffusion combustion in modern gas turbine engines is the production of NOx at a higher level which is not permissible for maintaining the healthy environment. Thus, combustion in lean premixed mode has become the most promising technology in many applications related to power generation gas turbine, industrial burner etc. Although the lean combustion minimizes NOx production, it suffers from an increased risk of lean blowout (LBO) when the requirement of thrust or load is low. It mainly occurs at the lean condition when the equilibrium between the flame speed and the unburnt air-fuel mixture velocity is broken. Current aircraft gas turbine engines operate fuel close to the combustion chamber which leads to the partially premixed combustion. Partially premixed combustion is also susceptible to lean blowout. Therefore, we have designed a swirl-stabilized dump combustor, where different lengths of fuel-air mixing are available. Our present work aims at improving the combustion stability by incorporating a secondary fuel injection through a pilot arrangement connected with the combustion chamber for premixed as well as partially premixed flames. Incorporation of the pilot system adds a small fraction of the total fuel into the combustion chamber directly. This investigation shows significant extension of the LBO limit towards leaner fuel-air mixture while the NOx emission in the combustion chamber is within the permissible limit. This result can be used for aircraft operators during the process of landing when fuel supply has to be decreased to reduce engine thrust or for power plants operating at low loads. The study of control is based on the colour variation of the flame which actually defines the changes in combustion characteristics. For early detection of LBO, the ratio between the intensity of red and blue colour obtained from flame images with a high speed camera is used. As LBO is approached, the ratio of red to blue intensity falls monotonically. When the ratio falls below a preset threshold, a small fraction of the total fuel is added to the central pilot line. This strategy allows the LBO limit to be shifted to a much lower equivalence ratio (maximum 20% and 11% for fully premixed and least premixed flames, respectively) without any significant increase in NOx production. The analysis includes a feedback control algorithm which is computed in MATLAB and the code is embedded in Labview for hardware implementation.
Engine Ground Start Characteristics of Fighter Aircraft at High Altitude Airbase
Authors: Kasram Santhosh , Manoharan Sajath Kumar , Padwale Mahesh P. , Ravishankar G. P.
Published: January 2020

The challenges faced during starting of an aircraft gas turbine engine using a Jet Fuel Starter (JFS) at high altitude airbase are discussed in this paper. Autonomous ground starts at high altitude airbase in soaked sub-zero temperature condition without any external ground support assistance is a challenge. Generally, the start cycle (sub-idle speed) at sub-zero temperatures of a gas turbine engine at high altitudes is influenced by several factors. Drag loads are estimated due to change in lube oil viscosity of engine gearbox and accessory gear box that affects available torque margin of a starter. These estimated loads are superimposed on starter characteristics to identify the available margins for successful starts. The cold start is particularly severe, since it increases the tip clearance between rotor and casing of the engine due to difference in its thermal growth. Higher tip clearances significantly degrade compressor surge margin and results in rotating stall. Inconsistent engine starts were resolved by adopting alternative methods without any change in hardware. This paper presents set of methods used to overcome inconsistent engine starts at high altitude cold weather conditions.
Experimental Analysis of Combustion in Gas Turbine
Authors: Murthy M. S. N. , Kumar Subhash , Sreedhara Sheshadri
Published: January 2020

This paper presents the methodology and results of an experimental analysis of combustion in a gas turbine combustor. The experimental setup is designed to imitate the conditions of a working gas turbine engine (GT), using an actual gas turbine combustor. Air is supplied by a heavy-duty air compressor at a maximum pressure of 7 bar to the combustor through an air pipe catering to the developing length. The air flow rate is measured using an ASME standard Venturimeter along with a manometer. The air flow rate and pressure are controlled by a combination of air outlet valve placed before developing length and by a throttle orifice in the exhaust duct at combustor outlet. Diesel fuel used in the experiments is provided at required atomizing pressure by a gear pump. Mass flow rate and pressure of fuel is controlled by combination of valves and varying the speed of gear pump using a variable speed electric motor. Combustion is initiated in a conventional pilot ignition unit using a spark plug and fuel burner. Fuel flow rate is measured accurately using a unique catch and time measuring system at the inlet of the gear pump.
Effect of Stator Variability on Axial Compressor Performance
Authors: Purushothaman Kirubakaran , Naveen Kumar N. R. , Pandurangi Vidyadheesh , Pratap Ajay
Published: January 2020

Variability in stator vanes is a widely used technique to improve the stability and efficiency of axial flow compressor in gas turbine engines. Most of the modern aircraft jet engines use variable stator vanes in both low pressure and high pressure compressors primarily for off-design performance. This study discusses in detail about the effect of stator variability in a three stage low pressure axial compressor at design and off-design conditions. Computational flow analysis were carried out for the three stage low pressure compressor with variability in inlet guide vane and first stage stator blade. Detailed investigation on flow physics was carried out in rotor blade passages with stator variability. At off-design speeds, the reduction in flow velocity is lower than the reduction in blade tip speed. This leads to mismatch in flow angles and inlet blade angles causing high incidence and large flow separation in blade passage. This results in poor aerodynamic stability of the axial compressor at off-design speeds. In this study, aerodynamic performance of compressor is evaluated from 70% to 100% design speeds with different stagger angle setting of inlet guide vane at each speed. Further, to improve 2nd stage rotor performance, variability was introduced in 1st stage stator blade and performance was evaluated. Compressor test results are compared with CFD data for design and off-design speeds.
Transient Response Characteristics of a Surface Junction Probe
Authors: Rout Anil Kumar , Sahoo Niranjan , Kalita Pankaj , Kulkarni Vinayak
Published: January 2020

The present work highlights the transient response phenomena captured by a coaxial surface junction thermocouple (CSJT) and subsequent use of the thermal probe for prediction of surface heat flux. To accomplish the objective, an E-type CSJT has been fabricated in-house in a laboratory scale from its thermo-elements with constantan (0.91mm diameter and 15mm length) serving as the inner element and chromel as outer element (3.25mm diameter and 10mm length). Both the thermo-elements are clubbed together coaxially which are separated by a thin layer of insulation in between them along the length. The junction between the thermo-elements is created at the surface through abrasion technique which forms a firm contact through formation of cold weld. The junction feature is then examined through a field emission scanning electron microscope (FESEM). The sensitivity of the probe is found experimentally to be 59 μV/°C.

The transient response characteristics are observed through water plunging and water droplet tests at 55°C for 20ms and 2s time scale. The voltage time data is recorded and with the help of sensitivity value, the temperature history is calculated. The temperature histories from plunging and droplet experiments are used for calculation of heat flux by analytically modeling the sensor as semi-infinite substrate and assuming heat conduction through it is one dimensional. The heat flux is also calculated from the same temperature history by using numerical analysis and compared with the previous one. The measured data provides substantial evidence for usage of these CSJT probes in transient temperature and surface heat flux recoveries within experimental time scale up to 2s with reasonable accuracy.
Vibration Mitigation of Rotors Suspended on Low-Cost Hybrid Gas Foil Bearing
Authors: Basumatary Kamal Kumar , Kalita Karuna , Kakoty Sashindra K. , Garvey Seamus D.
Published: January 2020

The hybrid Gas Foil Bearings combining the Gas Foil Bearing and Active Magnetic Bearing is a possibility for application in high-speed turbomachinery and a few developments have been made in this context. As such, the cost of conventional Gas Foil Bearing increases due to its requirement of precise manufacturing method and the coating material for the top foil and bump foil. In case of Active Magnetic Bearing, the normal electrical arrangement includes a multiplicity of independently controlled current sources usually at least four drives per bearing which increases its cost. Therefore, the hybrid Gas Foil Bearing will have much higher cost. In this work, a new electrical arrangement for the electromagnetic actuators of the hybrid Gas Foil Bearing has been proposed. The new arrangement requires only two drives per bearing and the bias current has been provided (in the same set of windings) through a simple rectifier with small series choke and shunt capacitor. As the number of drives required is less, the proposed bearing will have low cost. Implementing the new approach, the force vectors are achieved using only two current-source drives whereas the usual conventional arrangement requires four such drives. Numerical simulations are performed to explore the capabilities of the low cost bearing.
Entropy Generation Analysis of Mixed Convection Flow in a Nanofluid Filled Porous Cavity Using a Two-Component Lattice Boltzmann Method
Authors: Kashyap Dhrubajyoti , Dass Anoop K.
Published: January 2020

In the present work, a comprehensive analysis is made to understand the effect of velocity boundary conditions on the flow and thermal behaviour during mixed convection flow in a nanofluid-saturated porous square cavity. Two different velocity boundary conditions based on the movement of horizontal walls of the cavity are considered. The vertical fixed walls are differentially heated and the horizontal lids are thermally insulated. We have adopted the two-phase thermal lattice Boltzmann model (TLBM) for nanofluid system and modified this model to simulate nanofluid-filled porous medium by incorporating the Brinkman–Forchheimer-extended Darcy model. The current results provide good concordance with the published results computed through conventional numerical techniques. The detailed study of the heat transfer rate, entropy generation is made for discretely varying Richardson numbers (Ri) from 0.1 to 10 and Darcy numbers (Da) from 10−4 to 10−2 while maintaining Grashof number (Gr) at 104 and volume fractions of Cu nanoparticle (ϕ) less than equal to 5%. It is observed from the results that the optimal flow condition in terms of energy efficiency depends on the values of Ri and Da. From the viewpoint of both 1st and 2nd laws of thermodynamics, the performance of nanofluid is not satisfactory compared to the base fluid for current configurations as the augmentation of entropy generation with ϕ is more prominent compared to heat transfer enhancement.
Unsteady Non-Reacting and Reacting Flow Simulations of a Triangular Bluff-Body Flameholder
Authors: Mannari Manoj , Sriram A. T. , Singh Gursharanjit , Ganesan S.
Published: January 2020

Triangular bluff-body flame-holders, commonly called v-gutters, are used in gas turbine engine afterburners for flame stabilization. Unsteady flow dynamics in the v-gutter wake plays an important role in phenomenon such as combustion instability. The objective of the present work is to simulate the flow features for flow past v-gutter with Unsteady Reynolds-Averaged Navier–Stokes equations (URANS) and Large Eddy Simulation (LES) approach using Eddy Dissipation Model (EDM) for turbulent combustion. Volvo’s bluff body flame-holder rig configuration has been used for the current study. Both non-reacting and reacting simulations have been carried out in commercial Computational Fluid Dynamics (CFD) code FLUENT. In the case of non-reacting flow, the structure of instantaneous velocity field of LES differs from URANS approach. The predicted velocity profiles with LES have shown good agreement with the experiment in most of the regions than URANS for the case of non-reacting flow. In the case of reacting flow, LES simulations have shown unsteady flame with eddy structures. In contrast, URANS simulations have shown more like a steady flame. Overall, the temperature and velocity profiles were better predicted by LES than by URANS approach. In addition, simulations were carried out with circular flame-holder in an annular duct. The oscillation characteristics were found to be more or less similar for both straight and circular flame-holder.
Burning Characteristics of Boron/JP10 Nanofuel Droplets
Authors: Chandra Eshwar , Patel Ujas , Vinu R. , Sahu Srikrishna
Published: January 2020

The demand for higher volumetric calorific value of fuels for modern high performance aircraft has led to development of nanofuels that opens a promising future for enhancing the energy density of liquid fuels. This paper intends to study the effect of addition of boron nano-particles (NPs) on the burning characteristics of JP10 fuel droplets for various particle mass loadings (2%, 5%, 7% and 10%). Stable suspension of the NPs was achieved by adding Span80 and Tween80 as surfactant followed by ultra-sonication of the mixture. The fuel droplet was suspended on a horizontal quartz fiber. All experiments were conducted under atmospheric conditions. The droplet burning process was recorded using a high speed camera. The burning of pure JP10 and JP10 plus surfactant (without NPs) were also studied. In case of burning of pure JP10 fuel, the linear trend in time evolution of normalized droplet surface area suggested that the droplet burning follows the classical d2 – law and formation of bubbles inside the droplet was observed. However, these bubbles did not lead to puffing, which though occurred for JP10 plus surfactant (no NPs). This means that addition of surfactants, which has low burning rate, modifies the droplet burning process. In case of nanofuel droplet, burning occurs in different distinct stages for all mass loadings: initially the burning is smooth similar to pure fuel which is followed by intense periodical swelling and puffing in the later stages accompanied with ejection of secondary droplets from the parent droplet which burn separately. Finally, solo burning of NPs was evident for all cases. With increase in NPs loading from 2% to 10% vigorous surface oscillations and shattering of liquid masses were found which contributed to reduction in droplet lifetime. In such case the normalized droplet surface area showed periodic oscillations indicating departure from d2 – law.
Studies on the Outline of Flow Improvement With Speed Ratio in a Counter Rotating Turbine
Authors: Subbarao Rayapati , Govardhan M.
Published: January 2020

Flow through the Counter Rotating Turbine (CRT) stage is more complex due to the presence of two rotors that rotate in the opposite direction, the spacing between them and the tip clearance provided on rotors. This flow aspect may change, if we change the parameters like speed, spacing and blade angles. Current effort contains simulation studies on the flow topology of CRT through dissimilar speed ratios in the range of 0.85–1.17. CRT components stator and the rotors are modelled. At nozzle inlet, stagnation pressure boundary condition is used. At the turbine stage or rotor 2 outlet, mass flow rate is specified. Skin friction lines are drawn on rotor 1 as well as rotor 2 on all over the blade. Not much variation of skin friction lines is witnessed in rotor 1 on the pressure side with exception to the position of the separation line close to leading edge. On suction side, skin friction lines are more uniform when the speed ratio is greater than 1. Skin friction lines on rotor 2 pressure surface show the presence of re-attachment lines. The position of the nodal point of separation near the hub remained same, but the strength is decreasing with speed ratio. On rotor 2 suction side, near the tip, all along the stream wise direction, line of re-attachment is observed that spreads from leading edge to trailing edge, whose strength is varying with speed ratio. Near the hub as well, line of re-attachment is observed, which is of more intensity in lower speed ratios. For the same region in rotor 1, there is proper reattachment as nodes are observed instead of lines, suggesting that more improved flow is occurring in rotor 1 than rotor 2. Thus, the present paper identifies the flow modification with speed ratio in a counter rotating turbine. Also, effort is made to see the consequence of flow change on the output of CRT.
Numerical Simulation of the Effects of Manufacturing Deviations in Compressor Wheel Geometry on Performance
Authors: Ramachandran Dhinagaran , Mayandi Balamurugan , Dasappagoundenpudur Arthanarisamy Subramani , Murugan Vanamurthy , Boolingam Saravanan , Reddy Shanmugam Ranganathan
Published: January 2020

Increasingly stringent emission norms place tougher challenges on the efficiencies of a turbocharger. Higher efficiency requirement on turbocharger translates into tighter tolerances on the various geometrical dimensions. While this is applicable for all the components, in this study, the focus is on the compressor wheel. Compressor wheels are either cast or milled and variations are possible in either of the processes. Even small changes in the dimensions of compressor wheel (like diameter, angle distribution, thickness distribution, axial length and blade width etc.), cause the performance losses in Turbo charger. Loss in Performance of turbocharger affects Low-end torque, power rating, fuel economy as well as increasing compressor exit temperature. It is therefore important to understand and quantify the impact of the variation in blade geometry on pressure ratio, choke flow and efficiency. In this paper, a few case studies of manufacturing variations in blade thickness, blade height and axial length are shown based on gas stand tests as well as 3D CFD simulations. A process for extracting real geometry from white light scan data obtained from the manufactured wheel is shown which helps to compare the differences with the design intent geometry. Flow simulations with the real geometry show the impact on performance. Subsequently a systematic analysis of the variations is carried out to quantify the performance impact.
Design and Development of Diesel Turbocharger Compressor With Low-Pressure Ratio for Low BMEP Engines
Authors: Simonradha Franklin Praveen , Ramachandran Dhinagaran , Mayandi Balamurugan , Kashirajan Tamilarasan , Vengidasamy Alagarsamy , Boolingam Saravanan
Published: January 2020

As Indian OEMs are marching towards to meet the latest emission norms set by Government, the automotive industry is improving the performance of turbocharged internal combustion engines in terms of improved low-end torque, peak torque, peak power, fuel economy and reduced emissions. This, in turn, raises the demand for highly efficient turbocharging technology. The key strategy to improve turbocharger performance is to tailor the performance characteristics of the compressor. The type of turbocharger application governs the performance requirements of the compressor. Certain Indian commercial vehicle manufacturers in LCV segment especially tractor manufacturers apply low BMEP engines to have good durability and such applications require low-pressure ratio and wide flow compressors with peak efficiency island below the pressure ratio 1.3 to 1.4. A careful investigation is required to study the influence of compressor design features to design a low-pressure ratio compressor. However, the number of geometrical parameters influencing the compressor performance is high and investigating all the parameters may take a lot of time and computational effort. Furthermore, the trade-off between efficiency at low-end torque, peak torque, peak power and part-load efficiencies dictates the need for a multi-disciplinary optimization tool to design the compressor stage. The computational effort required to perform optimization through 3D CFD is also quite high. Hence, in this paper, we are introducing an approach to optimize the compressor design at multiple operating points through streamline calculations with the help of AxStream and validating the selected designs numerically through CFD and FEA calculations. This approach helps to design tailor-made compressors based on customer requirements and deliver the proto samples in a shorter period.
Design and Development of a Radial Turbine for Low Flow Turbocharging
Authors: Ramachandran Dhinagaran , Billa Srinivasa Rao , Mayandi Balamurugan , Balappan Perumal , Kanthila Shyamaprasad , Srivastava Neeraj
Published: January 2020

The scope of this study is to develop a turbocharger turbine wheel with improved aerodynamic performance at low mass flow rates and with reduced inertia for better transient response. The contrasting effect of geometrical shape and size parameters on the objectives of aerodynamic performance and transient response gives rise to the need to explore the design space for the best design having good trade-off between the multi-objective requirements. The search for an optimum aerodynamic design is a challenge due to structural requirements as well. A turbine wheel that is best suited for the current application is selected from the library as a baseline and this wheel is further optimized to meet the targets. Preliminary screening allowed the identification of parameters having major impact on the objectives and these results have been used to train a Response Surface (RS). Further, in the interest of reducing computational cost, a virtual optimization algorithm based on the RS has been employed to predict optimum design within the design constraints. The optimum designs thus obtained are validated with Computational Fluid Dynamics simulations for flow performance and Finite Element solver for satisfying structural requirements. This approach has allowed for application-based design of turbine wheel for instance, by changing key parameters like blade angle distribution, number of blades, axial length, blade height and width. An inertia reduction up to 10% has been obtained while retaining the performance at low mass flow rates.
Parametric Behaviour of Closed Loop Pulsating Heat Pipe in the Presence of Water As a Working Fluid
Authors: Yadav Nagendra P. , Madhuri  , Kumar Anil
Published: January 2020

This paper focuses on the parametric behavior of a closed loop pulsating heat pipe in the presence of water as a working fluid. The experimental study was done in the presence of different vacuum pressures inside the heat pipe with 50 percent filling ratio. The temperature was measured through the DAQ system with help of Lab VIEW 15.1 software at 12 locations of heat pipe at variable power inputs (10W–70W). Thermal resistance and variation of temperature are used to predict the performance of the heat pipe. Thermal resistance of heat pipe decreases with decrease in vacuum pressure inside the heat pipe. This work is useful for the transfer of heat of electronic devices and integrated circuit technology due to the high coefficient of convective heat transfer in the presence of phase change of working fluid inside the heat pipe.
Mechanism of highly selective SiO2 etching over Si3N4 using a cyclic process with BCl3 and fluorocarbon gas chemistries
Authors: Matsui Miyako , Usui Tatehito , Kuwahara Kenichi
Published: January 2020

A cyclic process using BCl3 and fluorocarbon gas chemistries was investigated for patterning a fine structure with a space width of 20 nm level. The relationships between etching parameters and cross-sectional pattern profiles were also analyzed to control the pattern profiles. This process alternately performs two steps: a deposition step using BCl3/N2/Ar plasma and an etching step using BCl3/CF4/Ar plasma with applying a wafer bias. The mechanism of the cyclic process was investigated by analyzing the surface chemistry at each step. Optical emission was also measured to clarify the reaction between F radicals and BClx radicals. The authors found the BClx layer formed on Si3N4 at the deposition step protected Si3N4 from etching by the reaction of BClx with CFx and F radicals at the etching step. Highly selective etching achieved a fine pattern structure by using BCl3/CF4/Ar plasma at the etching step. F radicals generated by the BCl3/CF4/Ar plasma had been scavenged by BClx radicals forming BFx to inhibit the Si3N4 etching effectively. In addition, B and BClx components adsorbed on the Si3N4 surfaces during the etching step protected Si3N4 from etching by reaction with F and CFx radicals. The adsorbed B and BClx desorbed from the surfaces by forming BFx, BClxF, and CClx, which remained on the Si3N4 surface. In contrast, the BClx layer became thinner on SiO2 than that on Si3N4 to promote ion-assisted etching of SiO2. This is because the BClx component has high reactivity with SiO2, and the remained CClx component was also consumed by the etching reaction with SiO2. The authors also found that ion flux at the etching step should be controlled to etch without shoulder loss, and ion energy at the etching step should be controlled to etch without footing shape at the bottoms of the pattern.
Making sense of the divergent series for reconstructing a Hamiltonian from its eigenstates and eigenvalues
Authors: Bender Carl M. , Brody Dorje C. , Parry Matthew F.
Published: January 2020

In quantum mechanics the eigenstates of the Hamiltonian form a complete basis. However, physicists conventionally express completeness as a formal sum over the eigenstates, and this sum is typically a divergent series if the Hilbert space is infinite dimensional. Furthermore, while the Hamiltonian can be reconstructed formally as a sum over its eigenvalues and eigenstates, this series is typically even more divergent. For the simple cases of the square-well and the harmonic-oscillator potentials, this paper explains how to use the elementary procedure of Euler summation to sum these divergent series and thereby to make sense of the formal statement of the completeness of the formal sum that represents the reconstruction of the Hamiltonian.
United Kingdom breaks from EU farm subsidies
Authors: Stokstad Erik
Published: January 2020

'Revolutionary' change will focus payments on environmental benefits, not food production.
Can do
Authors: Cornwall Warren
Published: January 2020

To forge a safer lining for food containers, a chemical company teams up with unlikely allies.
A notorious Nazi, revealed
Mengele: Unmasking the “Angel of Death”
David G. Marwell
Norton, 2020. 456 pp.
Authors: Rice Patricia Heberer
Published: January 2020

A U.S. Department of Justice insider's biography reveals new details about Josef Mengele
OXA-181-Producing Extraintestinal Pathogenic Escherichia coli Sequence Type 410 Isolated from a Dog in Portugal
Authors: Brilhante Michael , Menezes Juliana , Belas Adriana , Feudi Claudia , Schwarz Stefan , Pomba Constança , Perreten Vincent
Published: January 2020

Two multidrug-resistant and carbapenemase-producing
Escherichia coli
clones of sequence type 410 were isolated from fecal samples of a dog with skin infection on admission to an animal hospital in Portugal and 1 month after discharge. Whole-genome sequencing revealed a 126,409-bp Col156/IncFIA/IncFII multidrug resistance plasmid and a 51,479-bp IncX3
bla
OXA-181
-containing plasmid. The chromosome and plasmids carried virulence genes characteristic for uropathogenic
E. coli
, indicating that dogs may carry multidrug-resistant
E. coli
isolates related to those causing urinary tract infections in humans.
Antibiotic Degradation by Commensal Microbes Shields Pathogens
Authors: Gjonbalaj Mergim , Keith James W. , Do Mytrang H. , Hohl Tobias M. , Pamer Eric G. , Becattini Simone
Published: January 2020

The complex bacterial populations that constitute the gut microbiota can harbor antibiotic resistance genes (ARGs), including those encoding β-lactamase enzymes (BLA), which degrade commonly prescribed antibiotics such as ampicillin. The prevalence of such genes in commensal bacteria has been increased in recent years by the wide use of antibiotics in human populations and in livestock. While transfer of ARGs between bacterial species has well-established dramatic public health implications, these genes can also function in
trans
within bacterial consortia, where antibiotic-resistant bacteria can provide antibiotic-sensitive neighbors with leaky protection from drugs, as shown both
in vitro
and
in vivo
, in models of lung and subcutaneous coinfection.
Use of Rapid Diagnostics To Manage Pediatric Bloodstream Infections? You Bet Your ASP!
Authors: Gonzalez Mark D. , Yarbrough Melanie L.
Published: January 2020

Rapid diagnostic testing (RDT) can facilitate earlier optimization of the treatment of bloodstream infections, particularly in conjunction with an effective antimicrobial stewardship program (ASP). However, the effective implementation and workflow of RDTs are still a matter of debate, particularly in a pediatric setting. In this issue of the
Journal of Clinical Microbiology
, L. J. Juttukonda, S. Katz, J. Gillon, J. Schmitz, and R. Banerjee (J Clin Microbiol 58:e01400-19, 2020,
https://doi.org/10.1128/JCM.01400-19
) investigate the impact of a multiplex, molecular RDT on changes to antimicrobial therapy in an academic children’s hospital.