Engineering

Radio frequency identification (RFID) strap attachment modality is more reliable, low cost, and easy to assemble, and therefore, it becomes increasingly more popular in RFID tag designs. This paper presents a single-ended probe method with power transmission coefficient compensation for the characterization of RFID straps. Approximate identification of the Read/Write threshold power and impedance is based on the charge status of voltage multipliers and charge pumps instead of on the Read/Write-modulated commands. For comparison purposes, the conventional source-pull system is also briefly reviewed and applied to verify the measurement results of absorbing power and impedance of RFID straps using the presented method. An enhanced source-pull system, named RFID source-pull system, for an RFID strap that can accurately measure the threshold power and impedance for Read/Write-modulated commands is also constructed for verifying the presented method. Alien and Texas Instruments (TI) straps are used for measurement examples in this paper. It is found that the measurement results of both RFID straps obtained by the presented method agree well with those by the conventional source-pull system and the RFID source-pull system. The single-ended probe method can measure the approximate Read/Write threshold power and impedance of the RFID strap with minimum operating procedures; furthermore, the complicated radio frequency (RF) facilities are not required. Obtaining the Read/Write threshold power and impedance of RFID straps allows designers to estimate the maximum read range of the designed RFID tag in advance. Therefore, the implemented cost and design cycle times can substantially be reduced.

A two-dimensional numerical model of opposed flow flame spread over thin solid fuel is formulated and modeled to study the effect of gas phase heat sink (a wire mesh placed parallel to the fuel surface) on the flame-spread rate and flame extinction. The work focuses on the performance of the wire mesh in microgravity environment at an oxygen concentration 21%. The simulations were carried out for various mesh parameters (wire diameter, "d wr " and number of wires per unit length, "N") and mesh distance perpendicular to fuel surface "Y mesh ". Simulations show that wire mesh is effective in reducing flame-spread rate when placed at distance less than flame width (which is about 1 cm). Mesh wire diameter is determined not to have major influence on heat transfer. However, smaller wire diameter is preferred for better aerodynamics and for increasing heat transfer surface area (here prescribed by parameter "N"). Flame suppression exhibits stronger dependence on number of wires per unit length; however, it is relatively insensitive to number of wires per unit length beyond certain value (here 20 cm −1).

Scholars and scientists have been attempting to discover ways to control and lessen the reverberation of concurrent fires such as forest fires, building fires, and other various space fires but no convincing solutions have been concluded from their studies so far. The fundamental genesis of these types of fires concerns the unstable nature of the flames and considerable unpredictability associated with them. This led us to make an effort to study the etiquette of such flamesan experimental setup with rather ideal conditions was devised and an in-depth study was carried out. The present study predominately covers the study of fire propagation phenomena and the zeal of fire control in our daily life. This study includes the review of the varying regression rates and fire spread rates of flames as noticed in matchsticks when spaced in a linear orientation. The deportment instability of the flames will give us an insight into the heterogeneous fire propagation phenomenon and its control. Intuition into the heterogeneous fire propagation is expected for essential fire safety and, on its basis, an algorithm for the same is to be formulated. With this understanding along with the existing information, it might give us some possible solution to the reduction of such kinds of fires in buildings, forests, space propulsion systems and, large-scale fires in industries.

Scholars and scientists have been making efforts to discover ways to control and lessen the resonance of concurrent fires such as forest fires, and various space fires; however, no potential solutions have been concluded from their studies so far. The origin of these types of fires concerns the unstable nature of the flames and the considerable unpredictability associated with them. This work led us to do proper experimentation for the effect of sound on the spreading of the flames. Sound energy as a wave is always accompanied by compression and rarefaction. As an external effect, sound in the immediate vicinity of spreading flame can affect the flame spread rates. Appreciable work had been carried out however; the effect of sound on flames in a purely natural convective environment is an aspect yet to be thoroughly understood. Flame spread rate is a direct indication of forwarding heat transfer from burning to non-burning region. Formation of localized pressure and velocity fields occurs around the pilot fuel by the presence of sound waves. Change in heat transfer may results in increment or decrement in spread rates, when compared with one without sound. The present work attempts physical insight into the effect of sound frequency of intermediate range (3500 Hz to 7500Hz) on the spreading of flames in different configurations coupled with external sources. Results advocate the noteworthy impact of acoustics on the fire propagation phenomenon in distinct modes. Experimentation have revealed that acoustics has a critical influence on fire propagation, reducing the spread rate by 100 percent in a unilateral configuration.

Combustion is a complex phenomenon that involves the interaction of multiple phenomena, the cumulative effect of which give rise to the common flame that comprises wide range of practical, functional to propulsion applications. An interesting aspect that needs attention is the effect of the various surrounding environment phenomenon on its behavior and properties of premixed flames. It is noteworthy that soot formation is the main cause of pollution and a major cause of inefficiency of current propulsion systems. These phenomena root variety of energy interactions leading to energy transformations which in turn affect the flame behavior. Present work focuses on experimental investigations and implications of the externally induced acoustics on partially premixed flames. The subject is extensively studied as thermo-acoustics, and the current work emphases on studying its role on soot formation on premixed flames. Experimentation was carried out on a scaled setup comprising of a butan...

In the current scenario of space propulsion, liquid propellants have significantly proved useful in the upper stage rocket engines. Over the past couple decades, the world had inclined positively towards cryogenic fuel(s) viz., liquid oxygen and liquid hydrogen due to their high specific impulse. A higher specific impulse implies lower duration to achieve design cruise velocity for a given rocket initial and instantaneous mass. Liquid hydrogen and liquid oxygen as fuel and oxidizer can generate one of the highest enthalpy release in combustion, producing a specific impulse of up to 450 seconds at an effective exhaust velocity of 4.4 kilometres per second. Whereas, selected disadvantages are encountered in the form of storage and production. This indicates overdependence on cryogenic propellants and has necessitated the active research effort for better alternatives. As an interesting alternative, the combination of Dinitrogen Tetroxide (N2O4) and Monomethyl Hydrazine (MMH) have been...

Theory of special neurodiversity mandates the adjacent colonization of neurodiverse people with special needs for upgraded societal reforms and development. As the concept of a nation enfolds diverse geographical variations, the effectiveness of the theory of special neurodiversity can be optimized only if the controlling parameters are broadly understood and resolved in a unified way. For the enhanced socioeconomic growth of any nation, with the application of the theory of special neurodiversity, these variables are likely to affect the imperious restructuring which necessitates active research efforts to minimize their unreceptive impact. In view of the futuristic development, a simple youth-oriented sampling research survey was conducted to attain better physical insight about the geographical incongruities and their implications. The study attempts to examine the singular and coupled effect of key controlling geographic parameters viz., culture, climate, coordination, gender. Based on the results obtained, innovative modulations will be accorded in the prevailing RAS-VIN Model of Special Neurodiversity for enhanced socioeconomic growth and the contribution of special needs people. The understanding of geographical implications on the theory of special neurodiversity can be effectively applied on the wide range of administrative, institutional, organizational, engineering, humanities, and sciences applications explicitly aiming at upliftment and empowerment of special needs people.

The Combustion process in propulsion systems comprises of premixed flames and diffusion flames. As an active chemical propulsion system, the efficiency of operations depends significantly upon the type of combustion. In real cases, the transition of flames from one mode to another is noted in wide range of cases. This has necessitated research efforts to fundamentally understand the phenomenon for better combustion and thus better propulsion. The combustion transition from pre-mixed to the diffusion state is one of the least explored and quantitatively analysed domains. Present work, experimentally attempts to extensively study and quantify the physical causes thoroughly through manually induced transition in a butane-based cylinder fitted with a nozzle by using image processing techniques. The manually induced transition is processed by varying the inlet area for air entrainment. The phenomenon is systematically video-graphed and image segmentation is carried out to acquire the des...

Transitional phenomena of smoldering combustion over thin solid fuels are investigated. An experimental setup was upraised and implications of both smoldering and flaming external heat sources are estimated. Incense sticks were used as potential fuel and external smoldering heat source along with a fixed candle flame. The role of key controlling parameters, namely, separation distance and number of external heat sources in horizontal and vertical direction, was extensively examined. The surfacing issues of enclosure effect and the external heat sources orientation are addressed. The study primarily aims at understanding the feasibility and spontaneity of transition owing to external heat sources (both flaming and smoldering). Forward heat transfer significantly deviates qualitatively and quantitatively with varying separation distance in both directions. Number of external heat sources intensifies the transition phenomenon in smoldering combustion. With practical considerations, external heat sources arrangement and orientation have substantial effect on the combustion process.

Any application employing combustion places a huge emphasis on safe and effective operations. Several industries make use of relatively small amounts of propellant volumes to generate enormous amounts of energy. For instance, the Aerospace industry requires fuel injection in liquid rocket engines and gas turbine engines for producing thrust. For such cases, combustion comes with its own set of challenges. The predominant challenge among them all is that of combustion instability. Instabilities are physical phenomena occurring in both reacting and non-reacting flows. In the context of engine combustion, they tend to emanate from very small perturbations in the flow field and amplify in magnitude to alter the macroscopic properties of the flow causing problems for the smooth functioning of engines. Since the problem of combustion instability arises from the point of fuel injection itself, this project aimed to look at instability from the viewpoint of intermittent instability in the t...

Fires have been a serious threat yet to be comprehensively addressed, in safe air transportation. The fire occurrence in cabin is well etched by the unpredictable fire behavior transiting to larger high potential fires. The work investigates feasibility of automated ventilation jetfan in the aircraft to minimize fire spreading and enhance control action time, thus reducing fire hazards. Present work proposes utilization of jetfan as a potential fire safety system in aircrafts. Aircraft cabin is simulated as an enclosure with fire. Varying fire sizes are designed and placed at various locations in the enclosure. The physical insight is drawn using heat feedback mechanism. Parametric simulations were carried out on the governing parameters like, HRRPUA (Heat release rate per unit area), volume flow, jet-fan size and location. The effectiveness of jet fan and optimum location for varying fires is thoroughly analyzed. The work is motivated by the need to have better fire safety for safer aviation programs.

Introduction : Cotton mill workers in India constitute a large workforce, and are susceptible to number of diseases due to work-place environment. The present study has been conducted in rural area of South India to study the morbidity profile of cotton weavers using power looms at household levels. Methodology. Two hundred and ninety five power looms workers were included in a cross sectional study. Socio-demographic, occupational, work-place environmental, behavioral (including use of personal protective equipment) and morbidity data was collected through face to face interview and medical examination. Data were analyzed using SPSS software. Results:  The study revealed that the workers belonged to age groups 15 to more than 65 years, with females outnumbering males. 8.5% of workers smoked, and 45.4% gave history of alcohol consumption. Study of physical environment at workplaces showed that 87.1% workers were employed in overcrowded workplaces, 34.6% were working in suboptimal il...