External Stores Research Articles

공기력 및 구속 효과를 고려한 접힘 날개 전개 성능 분석

Recently, guided missiles applies folding wings to save space. During wing deployment, aero force acting on wing effects significantly on deployment performance, usually aerodynamic coefficient are calculated by CFD analysis. However, Missile Datcom can calculates estimated aerodynamic coefficient very quickly by assuming wing deployment motions as dihedral angle of wing. If missile has external store, wings may need to be folded on top of each other. In this case, one of wing help or interrupt other wing deployment, locking effect. In this study, both effects were included on wing deployment performance analysis to criteria for wings locked condition and formulated wing deploy performance, and compared with wind tunnel test data. Analysis predicted vulnerable wind direction of wing deployment very well.

Investigation of the Effect of Grid Size on External Store Separation Trajectory using CFD

In this paper, a numerical simulation of a finned store separating from a wing-pylon configuration has been studied and validated. A dynamic unstructured tetrahedral mesh approach is accomplished by using three grid sizes to numerically solving the discretized three dimensional, inviscid and compressible Euler equations. The method used for computations of separation of an external store assuming quasi-steady flow condition. Computations of quasi-steady flow have been directly coupled to a six degree-of-freedom (6DOF) rigid-body motion code to generate store trajectories. The pressure coefficients at four different angular cuts and time histories of various trajectory parameters and wing pressure distribution during the store separation are compared for every grid size with published experimental data.

Investigation of the Effect of Grid Size on External Store Separation Trajectory Using CFD

Investigation of the Effect of Grid Size on External Store Separation Trajectory Using CFD

The effects of sale signs on consumer intentions to visit a store

This study examines consumer attention to and the perceived aesthetics of sale signs, such as the designs (size and color) of the Point of Purchase (POP) sale signs outside shops, and how these factors affect consumer intention to visit a shop based on expectation regarding the stores. External store stimuli were created using the Sketchup 8 software package. Research found that influences on intention to visit a store can differ depending on how the sale signs are perceived. Consumer expectations of the store can differ depending on the size of sale signs and the colors employed. We expect that the outcomes of this study will aid fashion brands in designing sale signs that reflect their brand value and image. Sale sign planning and utilization as a part of the strategy will be the key factor that can affect consumer behavior.

Vibration analyses of an equivalent plate wing with an external store

Generally, pylon-mounted external stores significantly affect the aerodynamic characteristics of the aircraft due to their flexibility. Therefore, many investigations upon the dynamic and aeroelastic characteristics of an aircraft wing with external stores have been done over the last few decades Recently, a study was carried out regarding the aeroelastic effects on wings by the engine placement For severe operation conditions, classical linear theory with a small amount of amplitude vibration may not be an appropriate analysis. Nonlinear vibration analysis will be required, especially when the amplitude of the vibration is larger than the wing thickness. Chia performed static, dynamic, and post-buckling analyses of various isotropic and composite plates for that purpose. Dumir and Bhaskar derived finite element formulations to analyse the nonlinear vibration of beams and plates. Moreover, the variational-asymptotic plate formulation and the accompanying equations for the global analysis for the plates have been studied. That approach accounted every possible geometrical non-linearity associated with large displacement and small strain.

A comparative study of parameter estimation techniques applied to jettisoned external stores

AbstractThe present work evaluates the performance of different optimisation techniques on a parameter identification problem of aeronautical interest. In particular, the focus is on the classical Least Square (LS) and Maximum Likelihood (ML) methods and on the CMAES (Covariance Matrix Adaptation Evolution Strategy), DE (Differential Evolution), GA (Genetic Algorithm) and PSO (Particle Swarm Optimisation) Meta-Heuristic methods. The test problem is the reconstruction from flight test data of the aerodynamic parameters of an external store jettisoned from a helicopter. Different initial conditions and the presence of measurement noise are considered. This case is representative of a class of problems of difficult solution because of nonlinearity, ill-conditioning, multidimensionality, non separability, and fitness function dispersion. Only reference algorithm implementations found in literature are used. The performance of each algorithm are defined in terms of fitness function value, sum of absolute errors of the estimated coefficients, computational time and number of function evaluations. The results show the efficiency of CMAES in finding the best estimates with the least computational cost. Moreover, tests reveal that traditional methods depend heavily on problem characteristics and loose accuracy at the increase of the number of unknowns.

Calculations of the bounds on limit cycle oscillations in nonlinear aeroelastic systems based on equivalent linearization

The nonlinear aeroelastic system of an airfoil with an external store was investigated, with emphasis on the bounds of limit cycle oscillations (LCOs). Based on the equivalent linearization, an approach was proposed to calculate the bounds on LCOs over the full flight envelope. The bounds are determined directly without solving LCOs one by one as the flow speed varies. The presented approach can provide us with the maximal LCO amplitudes and the lower threshold for flow speed beyond which LCOs may arise. Numerical examples show that the obtained bounds are in nice agreement with numerical simulation results. The speed threshold can be predicted to a relative error less than 0.1%, and the maximal LCO amplitude to about 3%. The influences of the system parameters on the speed threshold for speed were investigated efficiently by the proposed approach.

What Role Do Local Grocery Stores Play in Urban Food Environments? A Case Study of Hartford-Connecticut

IntroductionResearch on urban food environments emphasizes limited access to healthy food, with fewer large supermarkets and higher food prices. Many residents of Hartford, Connecticut, which is often considered a food desert, buy most of their food from small and medium-sized grocery stores. We examined the food environment in greater Hartford, comparing stores in Hartford to those in the surrounding suburbs, and by store size (small, medium, and large).MethodsWe surveyed all small (over 1,000 ft2), medium, and large-sized supermarkets within a 2-mile radius of Hartford (36 total stores). We measured the distance to stores, availability, price and quality of a market basket of 25 items, and rated each store on internal and external appearance. Geographic Information System (GIS) was used for mapping distance to the stores and variation of food availability, quality, and appearance.ResultsContrary to common literature, no significant differences were found in food availability and price between Hartford and suburban stores. However, produce quality, internal, and external store appearance were significantly lower in Hartford compared to suburban stores (all p<0.05). Medium-sized stores had significantly lower prices than small or large supermarkets (p<0.05). Large stores had better scores for internal (p<0.05), external, and produce quality (p<0.01). Most Hartford residents live within 0.5 to 1 mile distance to a grocery store.DiscussionClassifying urban areas with few large supermarkets as ‘food deserts’ may overlook the availability of healthy foods and low prices that exist within small and medium-sized groceries common in inner cities. Improving produce quality and store appearance can potentially impact the food purchasing decisions of low-income residents in Hartford.

Limit Cycle Flutter Analysis of a High-Aspect-Ratio Wing with an External Store

Limit cycle flutter analysis of a high-aspect-ratiowing with an external store is presented. The concentrated store mass iscombined into the governing equations which are obtained using the extendedHamilton’s principle. The high-aspect-ratio wing structural model, which alsoconsiders the in-plane bending motion, is used. Three possible nonlinearitiesare considered including structural nonlinearities, aerodynamic nonlinearities,and store nonlinearities. Time simulation and bifurcation diagrams areperformed to analysis systems with three nonlinearities.

Design of a TFT-LCD Based Digital Automobile Instrument

The traditional mechanical instrument lacks the ability to satisfy the market with characters of favorable compatibility, easy upgrading, and fashion. Thus the design of a TFT-LCD (thin film transistor-liquid crystal display) based automobile instrument is carried out. With a 7-inch TFT-LCD and the 32-bit microcontroller MB91F599, the instrument could process various information generated by other electronic control units (ECUs) of a vehicle and display valuable driving parameters on the 7-inch TFT-LCD. The function of aided parking is also provided by the instrument. Basic principles to be obeyed in circuits designing under on-board environment are first pointed out. Then the paper analyzes the signals processed in the automobile instrument and gives an introduction to the sampling circuits and interfaces related to these signals. Following this is the functional categorizing of the circuit modules, such as video buffer circuit, CAN bus interface circuit, and TFT-LCD drive circuit. Additionally, the external EEPROM stores information of the vehicle for history data query, and the external FLASH enables the display of high quality figures. On the whole, the accomplished automobile instrument meets the requirements of automobile instrument markets with its characters of low cost, favorable compatibility, friendly interfaces, and easy upgrading.

Effects of Parameters on Flutter of a Wing with an External Store

The flutter analysis of a wing with an external store is presented. Because of the external store, the concentrated store mass is combined into the governing equations which are obtained using the extended Hamiltons principle. Dirac function is used to precisely consider the location and properties of the external store. The k method is used to calculate the flutter velocity. The effects of store parameters such as store mass and inertia on the flutter velocity are investigated.

Aeroelastic Tailoring of Oscillating Supersonic Wing with External Stores

This paper presents aeroelastic tailoring optimization of a swept back supersonic wing with external stores using composite structure material for the wing skin. The analysis has been conducted to calculate the flutter speeds at several altitudes ranging from a negative altitude of-7,943 ft until 30000 ft. MSC Nastran software is used to determine the flutter speed. The objective is to get the lowest possible wing weight by varying the wing skin composite fly angle and thickness as the optimization variables and by considering flutter speed as the optimization constraint. The constraint is imposed such that the flutter speed should be similar or higher than flutter speed of a previously investigated supersonic wing having similar planform but using aluminum as wing skin. The use of composite suggested that each composite layer thickness and fiber angle can be manipulated to achieve the target. The present results indicate that the weight of the composite wing skin can be reduced by 70 % compared to the aluminum wing skin while retaining similar or better flutter speed boundary envelope.

Time-Accurate Simulation of the Aircraft External Store Separation

Based on the original unsteady simulation program, the transonic aircraft external store separation was simulated by structured chimera grid approach coupled with a six degree of freedom trajectory code. The chimera grid utilized the hole-map cutting method; the searching efficiency was compared between the stencil walk and inverse map when building interpolation during the procedure. The space format utilized flux difference splitting format FDS based on Roe, moreover adding the min-mod limiter to achieve second order accuracy. The time format utilized the implicit integration and discrete scheme of the Back-Euler method. The three-dimensional trajectory of the store was captured and better fit for the experimental data. The results show that the method is correct and provides a reference for the simulation of the unsteady multi-body separation.

Time-Accurate Simulation of the Aircraft External Store Separation

Based on the original unsteady simulation program, the transonic aircraft external store separation was simulated by structured chimera grid approach coupled with a six degree of freedom trajectory code. The chimera grid utilized the hole-map cutting method; the searching efficiency was compared between the stencil walk and inverse map when building interpolation during the procedure. The space format utilized flux difference splitting format FDS based on Roe, moreover adding the min-mod limiter to achieve second order accuracy. The time format utilized the implicit integration and discrete scheme of the Back-Euler method. The three-dimensional trajectory of the store was captured and better fit for the experimental data. The results show that the method is correct and provides a reference for the simulation of the unsteady multi-body separation.

항공기 외장형 정찰 장비용 냉각 시스템의 성능 특성에 관한 실험적 연구

In this paper, we have proposed a vapor cycle refrigeration system as a cooling system to provide cooling air to the aircraft external reconnaissance stores. In the proposed vapor cycle system, receiver which prevents refrigerant from subcooling was eliminated and thermal expansion valve was replaced with electronic expansion valve. The vapor cycle refrigeration system is aimed to provide cooling air to the reconnaissance stores which is added to the aircraft in the form of external store. The wide temperature range of ambient air from the flight conditions can decrease the cooling performance and can make the refrigeration system unstable in low ambient temperature. Performance characteristics of the vapor cycle refrigeration system has been experimented under air conditions which is derived from the flight envelope. From the experiments, the vapor cycle refrigeration system has been proved to provide enough cooling air to the reconnaissance equipment and to be stable under all the flight conditions.

Deterministic pushdown-CD-systems of stateless deterministic R(1)-automata

Recently the one-counter trace languages and the context-free trace languages have been characterized through restricted types of cooperating distributed systems (CD-systems) of stateless deterministic restarting automata with window size one (so-called stl-det-R(1)-automata) that work in mode `=1' and that use an external counter or pushdown store to determine the successor components within computations. Here we study the deterministic variants of these CD-systems, comparing the resulting language classes to the classes of languages defined by CD-systems of stl-det-R(1)-automata without such an external device and to some classical language families, among them in particular the classes of rational, one-counter, and context-free trace languages. In addition, we present a large number of (non-)closure properties for our language classes.

시스템 추가장착을 위한 항공기의 안정성 해석

본 연구에서는 외부 장착물이 존재하는 항공기의 안정성 검증을 위해 진동 및 구조해석을 수행하였다. 외부 장착물이 존재하는 경우, 외부 장착물 자체의 정확성 및 안정성을 위한 요구조건이 주어지며, 이와 동시에 외부 장착물이 항공기에 장착되도록 개조된 항공기 구조물의 안정성 문제가 중요하다. 따라서 본 연구에서는 정적 상태에서의 고유주파수 계산을 통한 공진 여부를 조사하고 발사기를 장착하기 위해 개조된 구조물에 작용하는 진동하중을 구하였다. 또한 로컬 모델링 방법을 이용하여 추가 장착 구조물의 구조적 안정성을 검토하였으며 지상 및 비행시험을 통하여 이를 검증하였다. This paper presents the stability analysis of UH-60 helicopter with external store such like chaff/flare dispenser. An external store can affect the natural frequency of the aircraft and induce the resonance, which cause the failure of structures. In this paper, therefore, Rayleigh method is used to investigate the resonance with aircraft and external store, and transmission formula is used to determine the vibration load. Structural analysis with local modeling method are performed to present the robust design of aircraft with external store. The ground and flight test are also done to verify the stability of the aircraft.

An incremental method for limit cycle oscillations of an airfoil with an external store

This paper proposes an incremental method, which is based on the harmonic balance method, to analyze the nonlinear aeroelastic problem of an airfoil with an external store. The governing equations of limit cycle oscillations (LCOs) of the airfoil are deduced by the harmonic balancing procedure. Different from usual procedures, the harmonic balance equations are not solved directly but instead transformed into an equivalent minimization problem. The minimization problem is solved using the Levenberg–Marquardt method. Numerical examples show that the LCOs obtained by the presented method are in excellent agreement with numerical solutions. The bifurcation of the LCOs is further analyzed using the Floquet theory. It is found that the LCOs exhibit saddle-node, symmetry breaking and period-doubling bifurcations with the wind speed as control parameter. Compared with the harmonic balance method, the presented method has a wider convergence region and hence makes it easier to choose a proper initial guess for iterations.

Age-related changes in decision making: Comparing informed and noninformed situations.

Advantageous decision making progressively develops into early adulthood, most specifically in complex and motivationally salient decision situations in which direct feedback on gains and losses is provided (Figner & Weber, 2011). However, the factors that underlie this developmental improvement in decision making are still not well understood. The current study therefore investigates 2 potential factors, long-term memory and working memory, by assigning a large developmental sample (7-29 years of age) to a condition with either high or low demands on long-term and working memory. The first condition featured an age-adapted version of the Iowa Gambling Task (IGT; Bechara, Damasio, Damasio, & Anderson, 1994; i.e., a noninformed situation), whereas the second condition provided an external store where explicit information on gains, losses, and probabilities per choice option was presented (i.e., an informed situation). Consistent with previous developmental IGT studies, children up to age 12 did not learn to prefer advantageous options in the noninformed condition. In contrast, all age groups learned to prefer the advantageous options in the informed conditions, although a slight developmental increase in advantageous decision making remained. These results indicate that lowering dependence on long-term and working memory improves children's advantageous decision making. The results additionally suggest that other factors, like inhibitory control processes, may play an additional role in the development of advantageous decision making.

CD-systems of stateless deterministic R(1)-automata governed by an external pushdown store

Eine Kurzfassung dieser Arbeit ist zur Tagung SOFSEM 2011 eingereicht und akzeptiert worden. Sie wird im entsprechenden Tagungsband erscheinen: BOOKTITLE = SOFSEM 2011: Theory and Practice of Computer Science, Proc. AUTHOR = Nagy, B., Otto, F. TITLE = An automata-theoretical characterization of context-free trace languages SERIES = Lecture Notes in Computer Science 6543 PUBLISHER = Springer ADDRESS = Berlin YEAR = 2011 PAGES = 406-417