Network architecture and traffic transport for integrated wireless communications over enterprise networks

A novel network architecture based on the IEEE 802.6 metropolitan area networks (MAN) is proposed to integrate the wireless and wired segments of a regional enterprise network (REN) within a city. This architecture functions like a distributed switch for all types of services, reducing traffic congestion by sharing the high capacity link dynamically and facilitating signaling, mobility management, call processing and network management through its distributed functions, transport facilities and broadcasting capability. It also serves as a peripheral gathering network of REN traffic for transport over a wide area ATM/BISDN, enabling integration of an enterprise's regional networks into a global EN. Two major wireless applications, i.e., wireless PABX (WPABX) and wireless LAN (WLAN) are discussed to illustrate the advantages of this MAN‐based architecture. Although a REN is likely to support a wide range of different services, voice and data will continue to be the predominant traffic generated by WPABXs and WLANs, respectively, and are also representative of isochronous and asynchronous multimedia traffic carried by future wireless networks. We compare the traffic capacity of several voice transport alternatives under integrated (voice/data) network traffic with various data traffic loads, and study voice and data integration under three different integration schemes by simulations. Results indicate that the MAN‐based architecture is most effective employing queue arbitrated (QA) access for asynchronous traffic, pre‐arbitrated access for constant bit‐rate isochronous traffic, and the new reservation arbitrated (RA) access for variable bit‐rate isochronous traffic, under a scheme that permits full sharing between QA and RA traffic. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the Approximate Controllability of Some Semilinear Parabolic Boundary-Value Problems

We prove the approximate controllability of several nonlinear parabolic boundary-value problems by means of two different methods: the first one can be called a Cancellation method and the second one uses the Kakutani fixed-point theorem. Accepted 10 June 1996     

Amino wagging and inversion in hydrazine: K′ = 1 levels in the first excited state of the antisymmetric wagging vibration

The infrared absorption spectrum of NH₂NH₂ vapor has been observed in the region 899–1077 cm^?1, where the antisymmetric wagging band (v_a = 1 ← 0) appears, by the use of a Fourier transform spectrometer with a practical resolution of 0.003 cm^?1. In the region 925.0–925.6 cm^?1, the spectrum was also observed with a tunable diode laser, and a component, β, of the ^pQ₂ cluster has been further resolved. Most of the absorption lines assignable to β-^pP₂(J″), γ-^pP₂(J″), β-^pQ₂(J″), γ-^rQ₀(J″), β-^rR₀(J″), and γ-^rR₀(J″), where J″ = 2 ～ 15, have been identified. From these observed transition frequencies, in combination with the ground state energy levels given by microwave spectroscopy, the energy level structure of the K′ = 1 rotational states was determined. From this, the following molecular parameters for the v_a = 1 state were determined: molecular asymmetry, B′-C″ = 0.00017 cm^?1; a parameter q₅ describing an umbrella motion Coriolis interaction (q₅K) about the a axis, q₅ = ?0.0030 cm^?1; its J(J + 1) variation, q_5j = 0.00014 cm^?1; and a parameter describing an umbrella-motion K-type doubling g₅J(J + 1), g₅ = 0.000021 cm^?1.     

Autologlyphs

This column is a place for those bits of contagious mathematics that travel from person to person in the community, because they are so elegant, suprising, or appealing that one has an urge to pass them on. Contributions are most welcome.     

Single-wafer/mini-batch approach for fast cycle time in advanced 300-mm fab

Advanced 300-mm application specific integrated circuit/system-on-chip (ASIC/SOC) fabs with multiproduct and multiprocess models will require both a high level of flexibility and efficiency to achieve cost effective manufacturing cycle times. One of the main detractors for cycle time and fab flexibility is a batching requirement on certain types of processing that makes lots waiting for the batch to be completed and generates wip bubbles downstream. This paper reviews the front-end steps within a semiconductor manufacturing flow where batching requirements may be replaced by single-wafer or mini-batch alternatives for improved cycle time. Encouraging process results for front-end applications for potential single-wafer replacements are presented. It is demonstrated that single-wafer oxidation, LPCVD and cleaning offer a large potential cycle time gain but currently have different levels of maturity as potential batch technology replacements. In addition to the process feasibility, a DOE based on dynamic simulation is conducted enabling the quantification of potential gains in cycle time obtained by switching to single-wafer or mini-batch strategy instead of batch strategy, preferring integrated metrology and reducing mini-lots size. It shows that, in comparison to the baseline model (100%), the manufacturing cycle time may decrease down to 65% for mini-lots and to 78% for standard production lots.     

Regularization using a parameterized trust region subproblem

We present a new method for regularization of ill-conditioned problems, such as those that arise in image restoration or mathematical processing of medical data. The method extends the traditional trust-region subproblem, TRS, approach that makes use of the L-curve maximum curvature criterion, a strategy recently proposed to find a good regularization parameter. We apply a parameterized trust region approach to estimate the region of maximum curvature of the L-curve and find the regularized solution. This exploits the close connections between various parameters used to solve TRS. A MATLAB code for the algorithm is tested and a comparison to the conjugate gradient least squares, CGLS, approach is given and analysed.     

AIS Based Distributed Wireless Sensor Network for Mobile Search and Rescue Robot Tracking

This research presents the implementation of GSCF, an AIS-based control framework, on a distributed wireless sensor network for tracking search and rescue robots in open fields. The General Suppression Control Framework (GSCF) is a framework inspired by the suppression hypothesis of the immune discrimination theory. The framework consists of five distinct components; each carries a specific function that can generate long-term and short-term influences to other components by the use of humoral and cellular signals. The goal of the research is to develop mathematical models that can assist the control and analyses of robots behavior through the use of Suppressor Cells in the Suppression Modulator. Acquire data from the physical robot will be used as simulation parameters in future search and rescue research.     

Structures and electronic properties of AUn-1Cu and AUn （n ≤ 9） clusters

A systematic study on the structure and electronic properties of gold clusters doped each with one copper atom has been performed using the density functional theory. The average bond lengths in the Aun-1Cu （n ≤ 9） bimetallic clusters are shorter than those in the corresponding pure gold clusters. The ionization potentials of the bimetallic clusters Aun-1Cu （n 〈 9） are larger than those of the corresponding homoatomic gold clusters except for Aus. The energy gaps of the Au-Cu binary clusters are narrower than those of the Aun clusters except AuCu and Au3Cu. No obvious even-odd effect exists in the variations of the electron affinities and ionization potentials for the Aun-1Cu （n ≤ 9） clusters, which is in contrast to the case of gold clusters Aun.     

Characterization of nitrogen-doped ZnO thin films grown by plasma-assisted pulsed laser deposition on sapphire substrates

The crystalline, optical and electrical properties of N-doped ZnO thin films were measured using X-ray diffraction, photoluminescence and Hall effect apparatus, respectively. The samples were grown using pulsed laser deposition on sapphire substrates coated priorly with ZnO buffer layers. For the purpose of acceptor doping, an electron cyclotron resonance (ECR) plasma source operated as a low-energy ion source was used for nitrogen incorporation in the samples. The X-ray diffraction analyses indicated some deterioration of the ZnO thin film with nitrogen incorporation. Temperature-dependent Van der Pauw measurements showed consistent p-type behavior over the measured temperature range of 200–450 K, with typical room temperature hole concentrations and mobilities of 5×10¹⁵ cm⁻³ and 7 cm²/V s, respectively. Low temperature photoluminescence spectra consisted of a broad emission band centered around 3.2 eV. This emission is characterized by the absence of the green deep-defect band and the presence of a band around 3.32 eV.