Fire Resistance of Geopolymer Concretes

Geopolymer concrete has been proposed as an alternative to Portland cement concrete in applications requiring high degrees of fire resistance, because the intrinsic chemistry of the geopolymer binder does not require the retention of water or hydration within gel phases to maintain structural integrity of the binder. Portland cement concrete contains a high level of chemically bound water, which is essential to the gel binder structure, and which is lost upon heating to several hundred degrees Celsius, whereas the water present within a geopolymer concrete is overwhelmingly present in pores and is not an essential part of the strength-generating phases. However, predictions of geopolymer concrete fire performance have up to this time been based on small-scale laboratory testing (usually on paste or mortar specimens), rather than the study of large concrete sections, which provides significance to this work.

Posted in: Briefs, Materials, Composite materials, Heat resistant materials, Polymers, Fire

Tomographic Electrical Resistance-Based Damage Sensing in Nano-Engineered Composite Structures

Advanced composite materials are increasingly replacing metals in the aerospace industry as they offer weight-saving improvements such as high specific strength and stiffness, while providing resistance to fatigue and corrosion. Traditional advanced composites, however, exhibit significantly reduced electrical and thermal conductivity relative to metals, and matrix-rich regions at ply interfaces result in relatively poor interlaminar properties. Additionally, composites that have sustained damage often have non-visible or barely visible damage, complicating damage assessment. Recent efforts to address the limitations of advanced composites include the incorporation of carbon nanotubes (CNTs) to take advantage of intrinsic and scale-dependent properties of these nanostructures.

Posted in: Briefs, Materials, Aircraft structures, Composite materials, Conductivity, Nanomaterials

Uncooled Tunable LWIR Microbolometers

Uncooled infrared detectors have significant potential capabilities that have been little explored. Micro-machined uncooled detectors with tunable spectral characteristics across the long-wave infrared (LWIR, λ~8-12 μm) have been developed. In the middle wavelength infrared (MWIR) and LWIR regions, the fabrication of Fabry-Perot filters is more complex because the optical materials must be infrared-compatible and the layer thicknesses must be larger. It is very difficult to build filters for uncooled LWIR thermal detectors, which has limited previous researchers to demonstrations of discretely tunable 2- or 3-color thermal detectors rather than continuously tunable ones.

Posted in: Briefs, Physical Sciences, Architecture, Sensors and actuators, Thermal testing

Fluid Helmet Liner for Protection Against Blast-Induced Traumatic Brain Injury

An Advanced Combat Helmet liner design uses the novel idea of including filler materials inside channels in the liner. An energy-absorbing foam was selected for the main liner structure, and several filler material candidates of widely varying properties are being considered. To date, material has been evaluated both experimentally and numerically. Numerical studies will include coupled simulations with a detailed finite element head model, providing insight into the effect of the new liner on the brain’s response to a blast wave impact.

Posted in: Briefs, Physical Sciences, Finite element analysis, Foams, Head injuries, Protective equipment, Military vehicles and equipment

Performance of Steel Stud Walls Subjected to Blast Loads

Construction trends have brought about an increase in the use of cold-formed steel studs in Air Force facilities. These steel stud walls have significant potential for mitigating large blast events. The current state of steel stud research, however, has not addressed all the variables that can influence the behavior of typical wall systems. As a result, there is a research gap that exists in the blast-resistant design of conventional steel stud wall systems.

Posted in: Briefs, Physical Sciences, Materials properties, Steel, Protective structures, Construction vehicles and equipment

Programming Network Processors Made Simple

The telecommunications industry’s continuous strive for higher performance has spurred innovations in processor architectures. The general trend has been to go parallel; adding more cores to a single processor device and then dividing tasks between them. This has resulted in a more complex environment for software engineers to master. But does this mean that the programming of next-generation network processors (NPUs) has to be difficult? Not necessarily.

Posted in: Articles, Articles, Electronics & Computers, Architecture, Computer software / hardware

Designing Solid State Drives Into ATCA-based Platforms

Due to the growth of video on demand (VoD), IPTV media content, and embedded database applications, AdvancedTCA (ATCA)-based storage capacity requirements continue to increase exponentially. In addition, storage requirements have become more complex and varied for ATCA designs that have expanded beyond the central office to include network data center and general data center applications that need to handle a wide variety of server platforms. The advancements and general availability of new storage solutions, particularly solid state drives (SSDs), enables ATCA platform developers to meet the design metrics of a broader range of markets where distributed data storage and management become increasingly required. The continual evolution of SSD storage technology, with its improved capacity, performance, and cost reductions, provides additional opportunities for integrating storage directly into the ATCA platform, allowing new designs to gain the benefit of high performance and availability provided by ATCA-based systems.

Posted in: Articles, Articles, Electronics & Computers, Architecture, Computer software / hardware, Data management

Achieving Embedded Software Safety with Agility

Safety-critical development standards, such as DO-1781, have been very successful in guiding the production of reliable software. These standards assist developers in applying good software practices during development, ensuring, as much as possible, the absence of errors. Compliance with these stringent standards involves a high cost because of their labor-intensiveness and high levels of know-how.

Posted in: Articles, Articles, Electronics & Computers

Optimizing the Interoperability of Military Satellite Communications

Satellite communications offer mobility and communications for military operations in remote locations where terrestrial-based connectivity is not available, or is too expensive. Unfortunately, satellite connectivity brings many challenges that can impair network performance in delivering mission-critical information and applications. High-latency transport and application protocol inefficiencies, adverse weather, and interference are just a few of the causes that slow the delivery of applications and limit the amount of traffic that can run over a satellite link. Compounding these problems is interoperability among disparate military networks that can jeopardize mission-critical communications.

Posted in: Application Briefs, Application Briefs, Electronics & Computers, Optimization, Communication protocols, Satellite communications, Defense industry, Satellites

12-Volt System with Mini-ITX Motherboard

ITOX (East Brunswick, NJ) has partnered with Systium® Technologies to introduce the Model 132 “mini” series 12-volt system utilizing the ITOX NP101-D16C Mini-ITX motherboard. The Systium Model 132 “mini” series system platform is designed for cost-sensitive applied computing and x86 embedded systems applications requiring high-quality, long-life modular computing solutions. This is particularly applicable to medical electronics, industrial control, security and surveillance, telecommunications, ATM/POS, digital signage, gaming, and kiosk systems fields. The motherboard utilizes the 45nm 1.6 GHz Intel® AtomTM N270 processor with Intel 945GSE Express chipset and ICH7M I/O controller hub. The platform exhibits a thermal design power of less than 15 watts, delivering higher performance-per-watt than previous platforms. A single 12 VDC power input also reduces overall system configuration and operating costs.

Posted in: Products, Products, Electronics & Computers