Ultimate Capability Research Articles

The Ultimate's Detection Capability of Diversely Polarized Antenna Arrays using Higher Order Statistics

The use of diversely polarized antennas in an array system can significantly improve the overall's array performance. However, its capability does not get utilized to its full potential when the conventional array processing based on the second-order statistic of received signal is employed. The use of higher-order statistic in signal processing is presented in this work, where the performance enhancement is evaluated in terms of an ultimate's array detection capability that represents the system ability to correctly determine the total number of sources present in an environment. The analysis uses the differential geometry as a tool to analyze the geometrical shape of the corresponding diversely polarized manifold for different orders of statistic. Its intrinsic parameter is then used for the derivation of the detection's lower bound. The theoretical framework is supported by computer simulations to examine the detection capability for various types of antenna arrays with different orders of statistic.

Ultimate noise isolation in high‐speed digital systems on packages and printed circuit boards

A novel idea for ultimate noise isolation in high-speed digital systems on packages and printed circuit boards (PCBs) is presented. Ultimate noise isolation in high-speed digital systems on packages and PCBs can be achieved using the following concept: ‘a power island surrounded by a plurality of mixed alternating impedance electromagnetic bandgap (AI-EBG) structures-based power distribution network’. In this idea, the gap around the power island provides excellent isolation from DC to the first resonant frequency of the parallel plates in packages or in PCBs and mixed AI-EBG structures provide excellent isolation from around the first resonant frequency to a substantially infinite frequency. This novel structure is designed, fabricated, and measured, which demonstrates ultimate noise isolation capability in high-speed digital systems on packages and PCBs.

Failure Characteristics of Transmission Towers Subjected to Downbursts

Downbursts are recognized as a significant threat to safety of transmission towers. The difference between downburst and boundary layer wind profiles will lead to different failure modes and regions of damage of a transmission tower. To account for differences of wind profiles and failure modes, the different design wind loads are proposed, and a novel analytical framework is formulated for checking the section wind-resistance capability. The framework is useful for checking strength of transmission towers under downbursts. It has been found that the peak values of section moments exceed the ultimate section moment capability at about a third of the tower height under downbursts, while failure occurs in the bottom panel of tower under boundary layer winds. The results are consistent with the fact that regions of damage for most collapsed high-rise transmission towers under downbursts were indeed in lower-middle height of tower.

Buckling and ultimate capability of plates and stiffened panels in axial compression

This paper presents extensive non-linear finite element (FE) analysis and formulation development work carried out on the ultimate compressive strength of plates and stiffened panels of ship structures. A review of contemporary designs for large ships was carried out. The existing formulae for plate ultimate compressive strength were reviewed and compared with non-linear FE analysis results. A semi-analytical formula for ultimate compressive strength assessments of stiffened panels was proposed and is described. The developed formula was verified against results using ABAQUS non-linear FE software for a series of 61 stiffened panels and a good agreement between the proposed formula and FE results were achieved. The method was verified against a large number of published FE results and was also compared with 58 experimental results. The developed method was also applied to the deck and bottom structures for a range of various sizes oil tankers and bulk carriers.

Capacity of surface warship’s protective bulkhead subjected to blast loading

The protective bulkhead of the large surface warship need to be designed working in the membrane mode. In this paper, a formula is derived for calculating the plastic deformation of the protective bulkhead subjected to blast loading by the energy method, and the ultimate capability of the protective bulkhead can be calculated. The design demand of the protective bulkhead is discussed. The calculation is compared with external experiments, which indicates that the formula is of great application value.

Experimental Study on Anti-Impact Properties of Prestressed Concrete Beams

The dynamic displacement ductility and ultimate load-carrying capability of three partially prestressed concrete (PPC) and unbonded beams, has been experimentally investigated by applying impact load to their middle with falling hammers. The typical measurement wave curves are described. Influences of a falling hammer’s gravitational potential energy on the dynamic properties of the PPC beam are analyzed. Based on the analog simulation theory, the impact-load carrying capability of the actual unbonded PPC beam with span 12 m is gained. Results indicate that the unbonded PPC beams have favorable performance of anti-impact properties fragile destruction will not happen, and the unbonded PPC beams can be used in wide-span underground structures.

An evaluation of the performance of an uncooled microbolometer array infrared camera for transient thermography NDE

Transient thermography images of artificial defects in a carbon fibre composite test piece obtained using a cooled focal plane array (FPA) infrared camera are compared with those obtained using an un-cooled microbolometer array camera. Signal to noise ratios of each defect image are computed to provide an objective comparison of the performances of the two cameras. The cooled FPA infrared camera exhibits a higher ultimate defect detection capability than the un-cooled microbolometer array camera but this camera has the advantages of much smaller size and lower cost.

Unified Power Quality Conditioner for Compensating Voltage Interruption

This paper proposes a new configuration for the Unified Power Quality Conditioner, which has a DC/DC converter with super-capacitors for energy storage. The proposed UPQC can compensate the reactive power, harmonic current, voltage sag and swell, voltage imbalance, and voltage interruption. The performance of the proposed system was analyzed through simulations with PSCAD/EMTDC software. The feasibility of system implementation is confirmed through experimental works with a prototype. The proposed UPQC has ultimate capability to improve the power quality at the point of installation on power distribution systems and industrial power systems.

New Configuration of UPQC for Medium-Voltage Application

This paper proposes a novel configuration of a unified power quality conditioner (UPQC) which can be connected to the distribution system without series injection transformers. The operation of the proposed system was analyzed through simulations with PSCAD/EMTDC and experimental works with a scaled hardware model, assuming that the UPQC is connected with the 22.9-kV distribution line. The proposed UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules.

Reactive compatibilization of nylon 6/styrene–acrylonitrile copolymer blends: Part 3. Tensile stress–strain behavior

The stress–strain behavior of blends of nylon 6 (PA) and a styrene–acrylonitrile copolymer (SAN) compatibilized by an imidized acrylic polymer (IA) was evaluated in terms of the IA content and the dispersed SAN25 particle size. PA/SAN blends can be considered as a simpler version of industrially important PA/ABS blends; therefore, this study provides better understanding of the stress–strain behavior of compatibilized PA/ABS blends. The IA content was varied from 0 to 5 wt%; whereas the ratio of PA to SAN25 was held at 7/3; and in all cases the polyamide formed the continuous phase. From experiments using a Brabender batch mixer or an extruder as the mixing device, a reduction of dispersed particle size was observed with the addition of as little as 0.1 wt% IA. It was revealed from the experiments using a Brabender batch mixer that more than 0.5 wt% IA was necessary to prevent domain coalescence. The blends containing 1 wt% or more IA show necking and considerable plastic deformation. Transmission electron microscopy revealed that the normally brittle SAN25 particles were transformed into elongated shapes and undergo shear yielding under certain circumstances as the specimens experienced plastic deformation during stress–strain testing. Although the macroscopic elongation at break and the particle distortion ratio, which is defined as the ratio of the major axis to the minor axis of the elongated particles, are somewhat correlated, the local deformation in the neck region is much larger than the elongation at break. Thus, the ultimate capability for plastic deformation of the IA compatibilized blends is much larger than the overall elongation at break. The distortion ratio of the particles was observed to be as high as 6–7. There seems to be a relationship between the SAN25 particle size and the extent of plastic deformation realized. These experiments, however, do not differentiate the effect of diminishing particle size from increasing adhesion between the phases. Thus, it is not possible to assign unambiguously the dominant factor that permits the plastic deformation of the brittle SAN phase.

Watt-level Ka- and Q-band MMIC power amplifiers operating at low voltages

Ka- and Q-band watt-level monolithic power amplifiers (PAs) operating at a low drain bias of 3.6 V are presented in this paper. Design considerations for low-voltage operation have been carefully studied, with an emphasis on the effect of device models. The deficiency of conventional table-based models for low-voltage operation is identified. A new nonlinear device model, which combines the advantages of conventional analytical models and table-based models, has been developed to circumvent the numerical problems and, thus, to predict optimum load impedance accurately. The model was verified with load-pull measurements at 39 GHz. To implement a low-voltage 1-W monolithic-microwave integrated-circuit amplifier, careful circuit design has been performed using this model. A Q-band two-stage amplifier showed 1-W output power with a high power gain of 15 dB at 3.6-V drain bias. The peak power-added efficiency (PAE) was 28.5% and 1-dB compression power (P/sub 1 dB/) was 29.7 dBm. A Ka-band two-stage amplifier showed a P/sub 1 dB/ of 30 dBm with 24.5-dB associated gain and 32.5% PAE. Under very low dc power conditions (P/sub dc/<2 W, V/sub ds/=3.4 V), the amplifiers showed 29-dBm output power and PAE close to 36%, demonstrating ultimate low-power operation capability. To the best of our knowledge, this is the first demonstration of watt-level PA's under 3.6-V operation at 26 and 40 GHz. Compared with the published data, this work also represents state-of-the-art performance in terms of power gain, efficiency, and chip size.

Fabrication, Analysis, and Experimentation of a Practically Constructed Laminated Composite I-Beam Under Pure Bending

Seven I-beams constructed of AS4/3501 graphite/epoxy were tested and analyzed. The I-beams, having a layup sequence of 45/-45/03/-45/451T with various flange widths varying from ¾ to 2 ½ inches and a web height of 1 inch, were fabricated. The beams were tested under 4-point bending, producing results for the pre-buckled stiffness, buckling moment, and ultimate moment. Results indicate that wider flange beams exhibit buckling at lower moments than narrower flange beams. The flange width also affects the buckling mode. Wider flanged beams show larger edge displacements and lower mode values than narrower flanged beams. The ultimate moment capability appears to be only slightly increased by increased stiffness. Typically, increasing the flange width does not contribute significantly to the ultimate strength of the beam. For wider flanged beams, delamination occurs at the flange and then propagates to the web causing final failure. However, narrower flanged beams fail due to fiber/matrix crushing at the flange-web intersection.

Over-the-horizon radar surveillance of airfields for counterdrug applications

Airfield surveillance utilizing over-the-horizon radar (OTHR) offers the opportunity to gather significant intelligence concerning activity levels at suspect drug smuggling airports. It also provides the potential to classify aircraft initially from observed takeoff data, which would be helpful in interdiction efforts. This paper discusses the radar signal components and signal processing techniques required to accomplish this capability. An actual takeoff, observed by SRI International's Wide Aperture Research Facility (WARF), illustrates how the range-Doppler display plays an important role in developing and automating this capability. The ultimate capability is automatic takeoff recognition, initial target classification, rate of climb indication, and track to destination-all important contributions to the counterdrug command, control, and interdiction team.

Research and development on the utilization of alcohol fuels at the National Renewable Energy Laboratory

The U.S. Department of Energy's Alternative Fuels Utilization Program has been conducting research and development (R&D) on alcohol fuels since the 1970s. One of its objectives is to advance the technology and establish the ultimate performance capability of alcohol fuels in conventional engines. Early projects investigated the performance of low-level alcohol blends. The program expanded to encompass the benefits of mid-range blends and neat alcohol fuel applications. The current R&D program at the National Renewable Energy Laboratory concentrates on designing engines and emission control systems around the properties of neat alcohol fuels. This paper presents the current status of R&D efforts and prospects for future developments for optimizing the performance of alcohol-fueled vehicles.

Fast, very fast, and ultra-fast gas chromatography-mass spectrometry of thermally labile steroids, carbamates, and drugs in supersonic molecular beams

Gas chromatography-mass spectrometry (GC-MS) analyses of thermally labile compounds have been studied by using a short column fast gas chromatograph, coupled with fly-through electron ionization in supersonic molecular beams. Thirty-two compounds, which include steroids, carbamate pesticides, antibiotic drugs, and other pharmaceutical compounds, have been analyzed and the details of their GC-MS analysis are provided. The ability to analyze thermally labile compounds is discussed in relation to the speed of analysis. A new term, "speed enhancement factor" (SEF), is defined as the product of column length reduction and the carrier gas linear velocity increase, as compared with normal GC-MS conditions. Fast, very fast, and ultra-fast GC-MS are defined with a SEF in the ranges of 5-30, 30-400, and 400-4000, respectively. Trade-offs in the degree of dissociation, speed, gas chromatograph resolution, and sensitivity were studied and examined with thermally labile molecules. The experimental factors that affect the dissociation are described with emphasis on its reduction. We claim that the use of supersonic molecular beams for sampling and ionization provides the ultimate capability in the GC-MS of thermally labile compounds. The obtained 70-eV electron ionization mass spectra are shown, and an enhanced relative abundance of the molecular ion is demonstrated together with library search capability of these mass spectra, which is better than that reported with particle beam liquid chromatography-mass spectrometry. The performance of fast GC-MS in supersonic molecular beams is compared with other methods of fast GC-MS and with particle beam liquid chromatography-mass spectrometry.

Haemocompatibility of invasive sensors

In recent years the importance and utilisation of invasive chemical sensors have increased, especially in respect to their function and behaviour in a biological environment. This review aims to highlight the development of various sensors and reflect on the problems which can occur when the sensors come into contact with blood. Thus their haemocompatibility is a key area of importance. A clear understanding of their interaction with plasma proteins at the point of interface is fundamental as this determines their ultimate capability to function safely and effectively. There is also an overview of various techniques that have been developed, together with a broad summary of inherent problems which may arise when aiming to improve the haemocompatibility of invasive sensors for in vivo applications.

Advances in constant envelope coded modulation

An overview is given of recent advances in constant envelope combined coding and modulation. Modulation codes and trellises are discussed, and major classes of trellis modulation codes are described. Continuous phase modulation is defined, and concatenations of phase codes and convolutional codes are examined. The ultimate capability of phase modulation coding and the size of CPM trellis codes are addressed. Implementation issues are considered. >

Quantum-confined field-effect light emitters: device physics and experiments

Extended experimental results on three-terminal quantum-confined field-effect light emitters with current injection and field control of luminescent characteristics in the quantum-well structure are reported. By incorporating superlattice buffer layers (SLBLs), the quantum efficiency of the device is dramatically improved and equivalently nonradiative recombination processes are sufficiently suppressed at room temperature. The red-shift of the emission spectra by the quantum-confined Stark effect assures that the electric field is effectively applied to the quantum well. The experimental data on the transient responses of emission intensity to input voltage pulses show fairly good correspondences with theoretical prediction and previous photoluminescence experiments. The authors discuss the ultimate capability of high-speed switching and point that an optical pulse with a duration as short as 30 ps and involving more than 100 photons can be generated by scaling down the size of the device with 1% external efficiency. >

Osmium isotope analysis by inductively coupled plasma mass spectrometry

The rhenium-osmium decay scheme offers unique opportunities to study the age and origin of base and noble metal ore deposits. This requires the precise determination of Os isotope ratios, for which inductively coupled plasma mass spectrometry (ICP-MS) is ideally suited. An apparatus was constructed for direct distillation of OsO4 into the plasma, and was tested using a pure Os solution and a natural sulphide ore standard. Individual runs gave isotope ratio results with errors as low as 0.3%(1σ), while the means of all runs gave precisions as good as 0.3%(2σ) and accuracies of 0.1–0.2% against secondary ion mass spectrometry (SIMS) data. This demonstrates that Os isotope ratios can be measured to precisions and accuracies comparable to the ultimate capability of ICP-MS, despite concentrations in the low part per billion range. The technique is now poised for geological exploitation.

Dynamic fragility concepts for equipment design and qualification

Fragility concepts are explored for use in the design and qualification of nuclear plant equipment and for relating the ultimate capability of equipment to that of the overall plant. In the most general sense, the fragility level of a device may depend on several different types of environmental stress or challenge factors (i.e., heat, nuclear radiation, vibration, etc.) that influence its operation. However, emphasis is concentrated on the dynamic and particularly the seismic fragility levels of equipment. A general definition of dynamic fragility and various methods for its measurement are described. The state of published data on nuclear equipment fragility is discussed, and limitations on its use are noted. From there, the concept of a standardized seismic fragility data base and its potential uses are considered. Various gaps in the methodology are identified, and recommendations for further research are suggested.