Vibration Design Criteria for COTS-Based C4I Systems

1996 ◽  
Vol 39 (6) ◽  
pp. 28-32
Author(s):  
R. Normandy ◽  
Lindsay Yowell
Keyword(s):  
Dynamic Environment ◽  
Cost Effective ◽  
Design Criteria ◽  
Density Functions ◽  
Test Program ◽  
Isolation System ◽  
Standard Family ◽  
Spectral Density Functions ◽  
Comprehensive Test ◽  
Commercial Off The Shelf

This paper describes results of a planned comprehensive test program to identify the realistic dynamic environment commercial off-the-shelf (COTS) equipment will experience when utilized in Military Ground Mobile Command Control, Communication, Computer, and Intelligence (C4I) systems housed in DoD Standard Family Tactical Shelters. COTS equipment are generally designed for office use and lack robustness for military use in a ground mobile tactical environment. A realistic dynamic design criteria must be utilized for an appropriate mounting and/or isolation system design in the integration of a shelter. Acceleration spectral density functions are described to assist the designer in providing a COTS-based, survivable, cost-effective ground mobile tactical shelter-based C4I System.

A New Spectral Method for Modeling Dynamic Ice Actions

2004 ◽  
Author(s):  
Tuomo Ka¨rna¨ ◽  
Yan Qu ◽  
Walter L. Ku¨hnlein
Keyword(s):  
Dynamic Response ◽  
Spectral Density ◽  
Time Correlation ◽  
General Purpose ◽  
Density Functions ◽  
Offshore Structure ◽  
Spectral Density Functions ◽  
Ice Force ◽  
Ice Forces ◽  
Scale Data

This paper presents a method of evaluating the response of a vertical offshore structure that is subjected to dynamic ice actions. The model concerns a loading scenario where a uniform ice sheet is drifting and crushing against the structure. Full scale data obtained at the lighthouse Norstro¨msgrund is used in the derivation of a method that applies both to narrow and wide structures. A large amount of events with directly measured local forces was used to derive formulas for spectral density functions of the ice force. A non-dimensional formula that was derived for the autospectrum applies for all ice thicknesses. Coherence functions are used to define the cross-spectra of the local ice forces. The two kind of spectral density functions for local forces can be used to evaluate the spectral density of the total ice force. The method takes account of both the spatial and time correlation between the local forces. Accordingly, the model provides a tool to consider the non-simultaneous characteristics of the local ice pressures while assessing the total ice force. The model can be used in conjunction with general purpose FE programs to evaluate the dynamic response of an offshore structure.

Influence of Red Blood Cell Concentrations on the Measurement of Turbulence Using Hot-Film Anemometer

1983 ◽  
Vol 105 (4) ◽  
pp. 406-410 ◽  
Author(s):  
A. M. Sallam ◽  
N. H. C. Hwang
Keyword(s):  
Phosphate Buffer Solution ◽  
Experimental Information ◽  
Characteristic Change ◽  
Density Functions ◽  
Buffer Solution ◽  
Number Range ◽  
Flow Phenomenon ◽  
Human Red Blood Cells ◽  
Spectral Density Functions ◽  
Hot Film

Measurement of local velocity fluctuations was made with an L-shaped conical hot-film probe in a submerged circular jet. The experiment was carried out in solutions of washed human red blood cells (RBC) in a phosphate buffer solution (PBS), at hematocrit concentrations (Ht percent) of 10, 19, 29, and 38 percent. The viscosity of the testing solutions was kept at 3.2 c.p. by adding proper amount of dextran. The experiment was conducted at Reynolds numbers (NR) 674, 963, 1255 and 1410, based on the jet exit velocity and exit diameter. Statistical analyses were performed on the recorded instantaneous velocity signals to obtain the root-mean-square (rms) values, the probability density functions (PDF) and the power spectral density functions (PSDF) of the signals. Within the range tested, we noticed an incidental rise in rms values at 19 to 29 Ht percent for NR = 963 similar to those reported earlier in the literature. Further analyses using PDF and PSDF, however, showed neither a trend nor any physical significance of this rise. Based on the analyses of both the PDF and the PSDF, we believe that the incidental rise in rms value can be partially attributed to the high spikes registered by the probe in a high RBC concentrations fluid flow. The bombardment of RBC on the probe thermal boundary layer may cause a characteristic change in the probe response to certain flow phenomenon, at least within the Reynolds number range used in this study. Additional theoretical and experimental information is needed to pin point the nature of this response. We thus suggest that the second and higher moments of the HFA signals obtained in a fluctuating flow field involving a liquid with relatively high contaminant concentrations cannot be interpreted as a simple flow phenomenon.

scholarly journals Energy Efficient Lighting Design Criteria: Cost-Effective Solutions in an Industrial Environment

2007 ◽  
Author(s):  
Frank J. Agraz ◽  
John Maneri
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Return On Investment ◽  
Energy Savings ◽  
Cost Effective ◽  
Lighting Design ◽  
Design Criteria ◽  
Lighting System ◽  
Light Levels

The continual rising cost of energy, existing outdated lighting technology, and inefficient lighting designs have given property owners the opportunity to improve their facilities by retrofitting their existing luminaires with an energy efficient lighting system. A lighting retrofit uses the existing electrical infrastructure to replace, relocate, or convert existing luminaires with the latest generation of cost-effective components. New lighting technology has emerged within the last 6 years that generates energy savings of 40% to 50% while maintaining existing light levels. These upgraded and field-tested solutions lower energy consumption, generate a healthy financial return on investment, and can improve both the quality and quantity of light in the task area. As with any other solution, a cost-effective lighting system must be designed and engineered carefully to accommodate the needs of each work space. Simply installing a new lamp into an existing luminaire will not necessarily guarantee substantial energy savings or an improved lighting environment. In any space that uses electric lighting, the lighting designer must evaluate potential solutions for energy consumption, maintenance concerns, delivered light levels, hostile environments, and the overall economic impact of installing and long-term operation of the new system. In this paper, the author will discuss energy efficient lighting design criteria and how a lighting designer properly engineers a retrofit project to deliver energy savings without sacrificing light levels. The discussion includes a summary of both traditional and emerging technologies, and the long-term impact on energy consumption, maintenance, return on investment, lighting quality, and delivered light levels. Paper published with permission.

scholarly journals A Century of Riverbank Protection and River Training in Bangladesh

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3018 ◽  
Author(s):  
Knut Oberhagemann ◽  
A. M. Aminul Haque ◽  
Angela Thompson
Keyword(s):  
New Technologies ◽  
Low Cost ◽  
Dynamic Environment ◽  
Cost Effective ◽  
Lessons Learned ◽  
New Techniques ◽  
Middle Income ◽  
Knowledge Based ◽  
Protection Technology ◽  
River Training

Protecting against riverbank erosion along the world’s largest rivers is challenging. The Bangladesh Delta, bisected by the Brahmaputra River (also called the Jamuna River), is rife with complexity. Here, an emerging middle-income country with the world’s highest population density coexists with the world’s most unpredictable and largest braided, sand-bed river. Bangladesh has struggled over decades to protect against the onslaught of a continuously widening river corridor. Many of the principles implemented successfully in other parts of the world failed in Bangladesh. To this end, Bangladesh embarked on intensive knowledge-based developments and piloted new technologies. After two decades, successful, sustainable, low-cost riverbank protection technology was developed, suitable for the challenging river conditions. It was necessary to accept that no construction is permanent in this morphologically dynamic environment. What was initially born out of fund shortages became a cost-effective, systematic and adaptive approach to riverbank protection using improved knowledge, new materials, and new techniques, in the form of geobag revetments. This article provides an overview of the challenges faced when attempting to stabilize the riverbanks of the mighty rivers of Bangladesh. An overview of the construction of the major bridge crossings as well as riverbank protection schemes is detailed. Finally, a summary of lessons learned concludes the impressive progress made.

scholarly journals A Dynamic Testbed for Nanosatellites Attitude Verification

Aerospace ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 31 ◽  
Author(s):  
Dario Modenini ◽  
Anton Bahu ◽  
Giacomo Curzi ◽  
Andrea Togni
Keyword(s):  
Attitude Determination ◽  
Vision System ◽  
Ground Truth ◽  
Cost Effective ◽  
Air Bearing ◽  
Dynamic Testbed ◽  
Commercial Off The Shelf ◽  
Low Earth Orbits ◽  
Three Degree Of Freedom ◽  
Earth Orbits

To enable a reliable verification of attitude determination and control systems for nanosatellites, the environment of low Earth orbits with almost disturbance-free rotational dynamics must be simulated. This work describes the design solutions adopted for developing a dynamic nanosatellite attitude simulator testbed at the University of Bologna. The facility integrates several subsystems, including: (i) an air-bearing three degree of freedom platform, with automatic balancing system, (ii) a Helmholtz cage for geomagnetic field simulation, (iii) a Sun simulator, and (iv) a metrology vision system for ground-truth attitude generation. Apart from the commercial off-the-shelf Helmholtz cage, the other subsystems required substantial development efforts. The main purpose of this manuscript is to offer some cost-effective solutions for their in-house development, and to show through experimental verification that adequate performances can be achieved. The proposed approach may thus be preferred to the procurement of turn-key solutions, when required by budget constraints. The main outcome of the commissioning phase of the facility are: a residual disturbance torque affecting the air bearing platform of less than 5 × 10−5 Nm, an attitude determination rms accuracy of the vision system of 10 arcmin, and divergence of the Sun simulator light beam of less than 0.5° in a 35 cm diameter area.

The MIL-STD-1553B data bus: What does the future hold?

2007 ◽  
Vol 111 (1118) ◽  
pp. 231-246 ◽  
Author(s):  
D. R. Bracknell
Keyword(s):  
Cost Effective ◽  
Data Networks ◽  
Fibre Channel ◽  
Natural Choice ◽  
Operational Life ◽  
The Future ◽  
Future Data ◽  
Data Bus ◽  
Commercial Off The Shelf ◽  
Electro Magnetic

Numerous military platforms (land, sea and air) feature serial data bus technology based on the US MIL-STD-1553B data bus standard for integration of their digital systems. Many of these platforms have 15-20 years of operational life remaining, but the installed 1553B data buses (data networks) having only a 1Mbit/sec transfer rate are unable to meet many of the future data networking requirements. Research into new, higher performance data networks has concentrated on modern alternatives with throughput increases of two to three orders of magnitude (100Mbit/sec to 1Gbit/sec). These are generally based on modern commercial-off-the-shelf (COTS) standards, good examples being Ethernet and Fibre Channel. Some are already being employed in military platforms having been ruggedised for the harsh physical and electro-magnetic environment. However these COTS systems while being a natural choice for new platforms may not be cost effective for upgrading older platforms. This paper plots the history of MIL-STD-1553, possibly the most successful military platform standard of all time, and discusses some of the options for increasing its performance and economically extending its life into the future.

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