Bayesian inference and prediction of the inverse Weibull distribution for Type-II censored data

This paper describes the Bayesian inference and prediction of the inverse Weibull distribution for Type-II censored data. First we consider the Bayesian inference of the unknown parameter under a squared error loss function. Although we have discussed mainly the squared error loss function, any other loss function can easily be considered. A Gibbs sampling procedure is used to draw Markov Chain Monte Carlo (MCMC) samples, and they have in turn, been used to compute the Bayes estimates and also to construct the corresponding credible intervals with the help of an importance sampling technique. We have performed a simulation study in order to compare the proposed Bayes estimators with the maximum likelihood estimators. We further consider one-sample and two-sample Bayes prediction problems based on the observed sample and provide appropriate predictive intervals with a given coverage probability. A real life data set is used to illustrate the results derived. Some open problems are indicated for further research.     

Development of an RF Conditioning System for Charged-Particle Accelerators

Charged-particle accelerators use various vacuum windows on their accelerating radio-frequency (RF) cavities to throughput very high RF power. Before being placed on the cavities, the windows should be cleaned, baked, and fully RF conditioned to prevent a poor vacuum from outgassing, as well as other forms of contamination. An example is the coaxial fundamental power coupler (FPC) with an annular alumina ceramic window for each of the 81 superconducting RF cavities in the Spallation Neutron Source (SNS) linear accelerator. The FPCs needed to be tested up to 650-kW peak in a traveling wave and 2.6 MW with standing wave peaks in 1.3 and 60 pulses/s at 805 MHz. In this paper, an Experimental-Physics-and-Industrial-Control-System-based RF conditioning system for the SNS RF test facility is presented. This paper summarizes the hardware and software design strategies, provides the results obtained, and describes the future research scope.     

Decoder-assisted frame synchronisation for turbo-coded systems

An improved frame synchronisation methodology is proposed for turbo-decoded packets using a list synchronisation technique, where a simple synchroniser generates a list of most probable packet starting positions and the following synchroniser makes a refined decision. The second synchroniser is decoder-assisted, accepting soft-decision feedback from the decoder. The performance of the scheme is evaluated via simulation     

Low temperature nanointegration for emerging biomedical applications

In this paper, surface activated nanointegration of computational, electrical, optical, and mechanical structures for intelligent telemetry, communication, and sensing systems is described. The design approach and integration of top-down systems and bottom-up devices is considered with the need for biologically compatible bonding. For the simplified interface between bottom-up and top-down design a bus-bar unit architecture is presented. Emerging biomedical applications using intelligent sensors for remote patient monitoring and systems for rehabilitation comparing surface vs. implanted sensors are considered. Requirements for nanointegration of biomedical systems are suggested. Diverse combinations of rigid and flexible substrates of copper, gold, gallium arsenide, gallium phosphide and liquid crystal polymer were bonded by using two different nanobonding techniques. In these techniques, the surface cleaning with/without simultaneous deposition of nano-adhesion layers and contact in ultra-high vacuum/high vacuum were accomplished. These nanobonding technologies provide void-free, strong, and nanometer scale covalent bonding at room temperature or at low temperatures (～240 °C), and do not require chemicals, adhesives, or high external pressure. A considerable electrical current conduction and low loss of the nanobonded laminate was observed at high frequency. This investigation reveals that a biocompatible, high performance, and miniaturized systems may be realized for intelligent, implantable biomedical sensors because of the strong bond, low toxicity and favorable electrical properties in surface activated nanobonding.     

Surface activated bonding of LCP/Cu for electronic packaging

A lamination technique for liquid crystal polymer (LCP)/Cu was developed for high speed and high performance printed circuit boards (PCB). This approach was accomplished by using a modified surface activated bonding (SAB) process to achieve enhanced adhesion and a smooth interface. Systematic investigation of peel strength of four categories of samples, namely “as bonded”, “annealed”, “Cu-deposited”, and “Cu-deposited and annealed” showed highest peel strength in the “Cu-deposited and annealed” sample. Significant improvements in adhesion were observed in the samples cleaned with argon-radio frequency (Ar-rf) plasma (“as bonded” samples) followed by Cu deposition on LCP, which were heated after bonding in low vacuum pressure at 240∘C (about 70–75 times higher than that of “as bonded”). XPS analyses on peeled surfaces of the “Cu-deposited and annealed” sample reveal bulk fracture in the LCP. Threefold lower loss in conduction of SAB processed laminate than that of conventional heat laminate was most likely due to smooth interface of the SAB processed laminate (surface roughness was ninefold lower than that of conventional heat laminate). A plausible adhesion mechanism of Cu/LCP might be due to bonding of Cu adhesion sites to plasma induced dangling sites of LCP surface, and thermal reconstruction of Cu deposited layers.     

Delay‐insensitive identification of neighbors using unslotted and slotted protocols

For many applications, it is desirable for a node to be able to identify the neighbor nodes currently within range. However, the identification procedures for terrestrial communication networks (TCNs) are inefficient when implemented in long‐delay networks (LDNs) such as underwater acoustic networks or satellite networks, where the propagation time of a packet cannot be neglected. Here, we propose a time‐efficient and power‐efficient procedure, which is insensitive to propagation delay, for identifying neighbors in an LDN by optimizing the network offered load using either unslotted or slotted protocols. The procedure is adapted to the scenario when node cardinality and distribution are either known or unknown in advance. We achieve improvements as high as 80% in time and 45% in power consumption for our proposed approach compared with approaches developed previously for TCN. Furthermore, we analyze our proposed approach with the inclusion of the capture effect and packet receive time variations. We also provide a closed form formula for finding the optimum guard time and a procedure to estimate the packet receive time variations. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of bonding strength and sealing behavior of aluminum/stainless steel bonded at room temperature

This article reports the direct bonding of aluminum (Al) [99.999% (5N), 99% (2N)] and stainless steel SUS (304, 316) without heating for sealing in the ultra high vacuum (UHV) components. For bonding, the smooth surfaces of the Al and SUS specimens were activated using argon fast atom beam (Ar-FAB) for 1-60 and 60 min, respectively, in a background pressure of 6.0 × 10⁻⁵ Pa followed by close contact under an external pressure of 960 N. High bonding strength resulted in the bonded mates of Al and SUS304 activated for 30 and 60 min, respectively, due to the adhesion forces of the surface atoms. Tensile pulling tests showed bulk fractures in Al with impurity dependent bonding strength. The bonding strengths for the Al5N/SUS304 and Al2N/SUS304 specimens were higher than 60 and 100 MPa, respectively. For the sealing test, the smooth surface of the SUS316 flange containing a hole was bonded with Al after surface activation 60 and 30 min, respectively. Leak rates for Al5N/SUS316 and Al2N/SUS316 specimens were 1.5 × 10⁻¹¹ and 2.0 × 10⁻¹¹ Pa m³/s, respectively. These results satisfy the permissible leakage of a large-sized UHV chamber. Time dependence of the leak test behavior for both specimens shows a stable leak rate. Therefore, the sealing of Al/SUS316 may be utilized for the fabrication of corrosion free joints for fluid flow in the cooling of electron guns of small size equipment such as portable scanning electron microscopes in UHV pressure.     

Proposal for dispersion compensating square-lattice photonic crystal fiber

A dispersion-compensating square-lattice photonic crystal fiber for broadband compensation which covers the S, C and L communication bands, i.e. wavelength ranging from 1 460 nm to 1 625 nm is proposed in this paper. Theoretically, it is shown a negative dispersion coefficient of about-595 ps/(nm·km) to-1 288 ps/(nm·km) over S to L bands and-975 ps/(nm·km) at the operating wavelength 1 550 nm. The relative dispersion slope is perfectly matched to that of conventional single-mode fiber of about 0.003 6 nm^-1. Besides the proposed photonic crystal fiber shows the large nonlinear coefficient of 61.88 W/km at the operating wavelength of 1 550 nm. Moreover, the variation of structural parameters is also studied and discussed here.     

Approach for Grid Connected PV Management: Advance Solar Prediction and Enhancement of Voltage Stability Margin Using FACTS Device

The uncertainty in solar energy is different from conventional, dispatchable generation fuels and difficult to incorporate into the standard system operating procedures. In the first part of this work, the machine learning algorithm is used to train models based on solar irradiance data and different meteorological weather information to predict the solar irradiance for different cities to validate the forecasting model. Again, the intermittent and inertialess nature of photovoltaic (PV) systems can produce significant power oscillations that can cause significant problems with dynamic stability of the power system and also limit the penetration capacity of PV into the grid. In the second part, it is shown that the residue-based power oscillation damping (POD) controller obviously improves the inter-area oscillation damping. The validity and effectiveness of the proposed controller are demonstrated on the three-machine two-area test system that combines the conventional synchronous generator and flexible alternating current transmission systems (FACTS) device using simulations. This report overall puts an in-depth analysis with regard to the challenges of solar resources with integrating, planning, operating, and particularly the stability of the rest of the power grid, including existing generation resources, customer requirements, and the transmission system itself that will lead to an improved decision making in resource allocations and grid stability.     

Noncoherent decoder-assisted frame synchronization for packet transmission

We propose a noncoherent decoder-assisted (NDA) frame synchronizer, a two-stage, synchronization scheme based on the list-synchronization principle [P. Robertson, 1992], [M. Howlader and B. Woerner, 2001], for serially concatenated coded differential modulation (SCCD) system [K. R. Narayanan and G. L. Stuber, 1999] in packet transmission. For the first stage, we derive a suitable noncoherent maximum likelihood (SNML) rule, more effective for the noncoherent decoder's operating region of smaller channel phase offsets, to provide a reliable list of potential frame starting positions. For the second stage, we propose a hybrid sync method by exploiting the combined sign difference ratio (SDR) and sync word log-likelihood ratio (SW LLR) information [M. Howlader and B. Woerner, 2001] to obtain more reliable final decisions and reduce computational complexity. Performance and complexity of the proposed scheme are evaluated under constant and time-varying phase offsets in the AWGN channel via Monte Carlo simulation.