Design and analysis of contour bell nozzle and comparison with dual bell nozzle

The performance and the thrust delivery of the engine such as nozzles are in renovation for the greater performance. Modern combustion expansion system like in rocket nozzles will be updated with respect to the application. Bell and Dual bell nozzle is the One of such development. Four different types of Bell nozzle one duel bell nozzle is selected and studied using computational fluid dynamics (CFD) in the present paper. The project mainly focuses on design and analysis of contoured convergent divergent bell nozzle. For the simulation, consider  a 2D , parabolic contoured thrust optimized axisymmetric nozzle. The priority is  given to design a bell nozzle with negligible shock wave. The temperature effects are not taken into this study, the flow is purely cold flow (303K). A full length Bell nozzle created using Gambit software. The meshing and analysis of the Bell model were done using FLUENT software. Air is taken as working medium for the nozzle and also for the ambience. Only one half of the nozzle is simulated due to symmetry reasons, and symmetry boundary conditions are used at the corresponding planes. The nozzle walls were set as adiabatic and assumed to be hydraulically smooth. A control volume was constructed around the nozzle to take the interaction with the ambience. The behavior of flow along the bell nozzle is thus obtained

A Simple, Robust, and On-Site Microwave Technique for Determining Water-to-Cement Ratio (w/c) of Fresh Portland Cement-Based Materials

Inspection and evaluation of cement-based materials such as concrete is of great interest to the construction industry. In particular, real-time and on-site evaluation of water-to-cement ratio (w/c) is an important practical issue, since the compressive strength of a concrete structure is significantly influenced by its w/c. Currently, there is no single real-time, on-site, relatively in-expensive, easy-to-implement, and operator friendly technique for evaluating this parameter. Microwave nondestructive testing and evaluation techniques have shown great promise when used for inspection and evaluation of the properties of cement-based materials. In this paper, the optimal design of a monopole antenna probe used to evaluate w/c of fresh cement-based materials in real-time and in-situ is presented. This probe, operating at 3 GHz, is used along with a reflectometer whose dc output voltage is shown to be linearly correlated to w/c of fresh cement paste and fresh concrete specimens. This paper presents the optimal probe design procedure, the experimental verification of the results, and the results of using the custom-made reflectometer for quick and robust w/c measurement of fresh cement paste and concrete

Interior Atmosphere: Does It Really Have an Impact on Consumer Purchasing Behavior at Self- Serving Convenience Stores?

The main aim of this study was to investigate the impact of interior store atmosphere on consumer purchasing behavior at self-serving convenience stores in Ampara District, Sri Lanka.  Today, retail industry became highly competitive with the increasing number of convenience and other types of retail stores in the area. Hence, the retailers need to be more customer focused and have to differentiate from their competitors by making their interior atmosphere more attractive to consumers and to encourage them to spend more time, money, to purchase more merchandises and to stimulate their repeat purchase intention. A survey research was employed to collect primary information from 292 customers from convenience stores in Ampara District. Interior atmospheric factors such as, music, scent, light and color were used to identify the impact of interior atmosphere on consumer purchasing behavior. Convenience sampling was employed for data collection using a questionnaire with a five-point Likert scale. SPSS 20.0 was used to analyze the data. Significant interior atmospheric factors that influence consumer purchasing behavior included music, scent, light and it is found out that color has no any impact on consumer purchasing behavior. Keywords: Interior atmosphere, convenience stores, consumer behavio

Parameterization Models for Traceable Characterization of Planar CPW SOL Calibration Standards

International audienceMethods for traceable characterization and uncertainty evaluation of planar 1-port CPW short-open-load (SOL) devices are developed. The agreement of modelling and verification measurement results greatly supports the application of the proposed parameterization models and used FEM-based EM modelling of CPW structures for traceable characterization of planar CPW-based SOL devices in the frequency range between a few kHz up to 50 GHz

Multiport Vector Network Analyzer Configured in RF Interferometric Mode for Reference Impedance Renormalization

International audienceA novel active microwave interferometric technique is implemented on a multiport vector network analyzer for renormalizing the reference impedance 50 Ohms into any desired complex impedance. The resulting measured reflection coefficient around the new reference impedance is around zero, resulting in high measurement sensitivity. The method proposed avoids any external component commonly found in interferometric setups. In addition, a zeroing process including vector calibration is developed for broad frequency range and requires only a software procedure to be implemented in the system framework

Dielectric Plug-Loaded Two-Port Transmission Line Measurement Technique for Dielectric Property Characterization of Granular and Liquid Materials

There are numerous dielectric property characterization techniques available in the microwave regime each with its own uniqueness, advantages and disadvantages. The two-port completely-filled waveguide (transmission line) technique is a robust measurement approach which is well suited for solid dielectric materials. In this case, the dielectric material can be relatively easily machined to fit inside the waveguide and the subsequent measurement of the scattering parameters of this two-port device renders the dielectric properties of the material filling the waveguide. However, this technique is not well suited for measuring the dielectric properties of granular and liquid materials. These materials are used in the production of various composites which are increasingly replacing the use of metals in many environments. If this technique is directly applied to these types of materials, several approximations either in the measurement apparatus or the formulation must be made. To overcome this problem, this paper describes a modification to this measurement technique utilizing two dielectric plugs which are used to house the granular or the liquid dielectric material. In this approach no approximation to the measurement apparatus is made while the presence of the plugs are fully accounted for in the derivations. Using this technique, the dielectric properties of cement powder, corn oil, antifreeze solution and tap water, constituting low- and high-loss dielectric materials (granular and liquid) were measured. In addition, the important issue of measurement uncertainty associated with this technique is also fully addressed. The issue of optimal choice of various measurement parameters is also discussed as it relates to the measurement uncertainty

Punching Shear Characterization of Steel Fiber-Reinforced Concrete Flat Slabs

Punching shear failure in thin slabs under concentrated loads can cause shear stresses near columns. The use of steel fiber is a practical way to improve a slab-column connection's punching strength and deformation capacity. In this study, the capacity and behavior of steel fiber-reinforced concrete flat slabs are examined under punching shear force. Ten small-scale flat slabs were tested, eight of which had steel fiber and two without. Two parameters are studied in this paper, which are the fiber volume ratio (from 0% to 2%) and the stub column load shape (circle and square). The test results include the concrete compressive strength, crack patterns, punching shear, and load-defection behavior of the slabs. Based on the experimental results, it was found that the punching shear capacity of slabs with steel fiber (S5) increased by 21.8% compared to slabs without steel fiber (S1), and the slabs with steel fiber had more ductility compared to the slabs without fiber. Doi: 10.28991/HIJ-2022-03-04-08 Full Text: PD

Barriers to Attracting Private Sector Investment in Public Road Infrastructure Projects in the Developing Country of Iran

Abstract Private sector investment, the mainstream financing method for procuring public road transport development projects, has encountered several profound difficulties and risks during execution, particularly in developing countries. However, there needs to be more extensive investigations on the major barriers facing road transport infrastructure projects in these countries. In this vein, the present study aims to identify and assess the perceived barriers inhibiting private sector investment in delivering public road transport infrastructure projects in the developing country of Iran. The research method adopted is based on a descriptive survey with a three-round Delphi technique with 35 experts from both the private and public sector in Iran. According to the research study results, four main groups of legal and organizational, political, economic, and operational barriers have been found to significantly impact the attraction of private sector investment in such projects. The three most significant obstacles for public road transport infrastructure projects in developing countries include: (i) a lack of financial and investment safety; (ii) a lack of proficient managers and policies of public organizations in order to facilitate the process of privatization; and (iii) corruption in the privatization process. The survey findings can help the government and policymakers to eliminate or alleviate the potential barriers towards private sector participation in future public road infrastructure projects, particularly in those developing countries such as Iran

Clinical profile of dengue fever infection in patients admitted in tertiary care centre Agroha, Hisar, Haryana, India

Background: Dengue infections can result in a wide spectrum of disease severity ranging from an influenza-like illness (dengue fever; DF) to the life-threatening dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). The study was aimed to compare the clinical profile of all patients diagnosed with dengue viral infection at MAMC.Methods: This retrospective study included 188 patients infected with dengue virus, age 6 years to 70 years. Laboratory and haematological data were included.Results: Peak of infection occurred in October 2015 and least number of cases were recorded in December 2015. Common clinical symptoms were fever, and abdominal pain. Common haematological abnormalities were thrombocytopenia and leucopoenia. All patients survived. There was no case of dengue hemorrhagic fever or dengue shock syndrome.Conclusions: Significant differences in the clinical profile is possibly because of infection with different serotypes of dengue virus (DENV), concurrent/sequential infection of more than one serotype, and differences in host immune responses associated with host genetic variations

Evaluation of pharmacological and catalytic activity of CuO and Zn doped CuO nanoparticles

124-129CuO and Zn doped CuO nanoparticles (Zn-CuO NPs) with varying concentration i.e., ZnxCu1−xO (where x = 0, 0.5, 1, and 1.5%) have been prepared via microwave assisted method. The spheroid structure of CuO NPs and the nanorod structure of Zn- CuO NPs have been determined using High Resolution Scanning Electron Microscopy (HR-SEM) analysis. Elemental analysis has been carried out using Energy Dispersive X-ray Analysis (EDAX). The particle size and surface area of CuO and Zn-CuO NPs have been confirmed by Brunauer–Emmett–Teller (BET) method. The antibacterial studies have been revealed that Zn(1.5%)-CuO NPs exhibited maximum zone of inhibition (19-29 mm) against the tested four bacterial strains. Zn-CuO NPs have been displayed robust action of antibacterial activity with minimum inhibitory concentration (MIC) of 0.09 μM against Campylobacter coli (C. Coli). DPPH and H2O2 radical scavenging assay investigation have been revealed that the significant scavenging activity has showed by Zn(1.5%)-CuO. The in vitro cytotoxicity evaluation of synthesized material against human breast (MCF7) and human lung (A549) cancer cell lines have been demonstrated that Zn(1.5%)-CuO NPs exhibited better cytotoxic activity against MCF7 cell lines (97.5% cell death) than A549 cell lines (90% cell death)