21,770 research outputs found
An eco-solution for track & trace of goods and third party logistics
This paper presents a new economic cost-effective solution known as the Web and telephony based method for tracking and tracing of goods and small and medium sized third party logistic providers. Considering that these companies usually operate on very flat margins, a comparison is made of the available track and trace technologies like GPS, mobile phone approximated GPS and Java based cell tracking in terms of costs, operating risks, and other evaluation criteria
Three dimensional thermal analysis of rocket thrust chambers
A numerical model for the three dimensional thermal analysis of rocket thrust chambers and nozzles has been developed. The input to the model consists of the composition of the fuel/oxidant mixture and flow rates, chamber pressure, coolant entrance temperature and pressure, dimensions of the engine, materials and the number of nodes in different parts of the engine. The model allows for temperature variation in three dimensions: axial, radial and circumferential directions and by implementing an iterative scheme, it provides nodal temperature distribution, rates of heat transfer, hot gas and coolant thermal and transport properties
Application of the LQG/LTR technique to robust controller synthesis for a large flexible space antenna
The problem of synthesizing a robust controller is considered for a large, flexible space-based antenna by using the linear-quadratic-Gaussian (LQG)/loop transfer recovery (LTR) method. The study is based on a finite-element model of the 122-m hoop/column antenna, which consists of three rigid-body rotational modes and the first 10 elastic modes. A robust compensator design for achieving the required performance bandwidth in the presence of modeling uncertainties is obtained using the LQG/LTR method for loop-shaping in the frequency domain. Different sensor actuator locations are analyzed in terms of the pole/zero locations of the multivariable systems and possible best locations are indicated. The computations are performed by using the LQG design package ORACLS augmented with frequency domain singular value analysis software
Conditional operation of a spin qubit
We report coherent operation of a singlet-triplet qubit controlled by the
arrangement of two electrons in an adjacent double quantum dot. The system we
investigate consists of two pairs of capacitively coupled double quantum dots
fabricated by electrostatic gates on the surface of a GaAs heterostructure. We
extract the strength of the capacitive coupling between qubit and double
quantum dot and show that the present geometry allows fast conditional gate
operation, opening pathways to multi-qubit control and implementation of
quantum algorithms with spin qubits.Comment: related papers here: http://marcuslab.harvard.ed
A survey of thermodynamic properties of the compounds of the elements chnops progress report, 1 feb. - 30 jun. 1965
Heat capacities, entropies, enthalpies, and free energies of organic and inorganic compounds of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfu
Relationships between different nutritional anthropometric statuses and health-related fitness of South African primary school children
Background A double burden of both under- and over-nutrition exists among South African children. Aim Describe associations between nutritional statuses and health-related fitness test performances. Subjects and methods Height and weight of 10 285 children (6-13 years; n=5604 boys and 4681 girls) were measured and used to calculate: body mass index (BMI), and prevalence of overweight and obesity, stunting, wasting, and underweight. Physical fitness scores for standing long jump, shuttle run, sit-and-reach, sit-up (EUROFIT) and cricket ball throw were assessed. Age and gender specific z-scores were calculated for these variables. Physical fitness for each nutritional status group was compared to children of normal weight. Results Compared to normal weight children, overweight and obese children scored lower on all fitness tests (p<.001), except cricket ball throw (p=.235) and sit-and-reach (p=.015). Stunted and underweight children performed poorer than normal weight children on most fitness tests (p<.001), except sit-and-reach (stunted: p=.829; underweight: p=.538) and shuttle run (underweight: p=.017). Performance of wasted children was not as highly compromised as other undernourished groups, but they performed poorer on the cricket ball throw (p<.001). Conclusions When compared to normal weight children, both under- and over-nourished children performed poorer on some, but not all, health-related fitness tests
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