Design considerations for a monolithic, GaAs, dual-mode, QPSK/QASK, high-throughput rate transceiver

A monolithic, GaAs, dual mode, quadrature amplitude shift keying and quadrature phase shift keying transceiver with one and two billion bits per second data rate is being considered to achieve a low power, small and ultra high speed communication system for satellite as well as terrestrial purposes. Recent GaAs integrated circuit achievements are surveyed and their constituent device types are evaluated. Design considerations, on an elemental level, of the entire modem are further included for monolithic realization with practical fabrication techniques. Numerous device types, with practical monolithic compatability, are used in the design of functional blocks with sufficient performances for realization of the transceiver

Advanced digital modulation: Communication techniques and monolithic GaAs technology

Communications theory and practice are merged with state-of-the-art technology in IC fabrication, especially monolithic GaAs technology, to examine the general feasibility of a number of advanced technology digital transmission systems. Satellite-channel models with (1) superior throughput, perhaps 2 Gbps; (2) attractive weight and cost; and (3) high RF power and spectrum efficiency are discussed. Transmission techniques possessing reasonably simple architectures capable of monolithic fabrication at high speeds were surveyed. This included a review of amplitude/phase shift keying (APSK) techniques and the continuous-phase-modulation (CPM) methods, of which MSK represents the simplest case

Investigating municipal solid waste management system performance during the Arba’een event in the city of Kerbala, Iraq

Every year, many religious events attended by 300 million pilgrims take place in many holy cities and sites around the world. However, research on municipal solid waste is limited despite the reputation of religious events to generate substantial amounts of waste. This research aims to address this gap and contribute to new knowledge on municipal solid waste management at religious events by investigating and evaluating the municipal solid waste management system applied at the Arba’een event in Kerbala, one of the largest religious events in Iraq. Field observations and in-depth interviews with nine senior managers from Kerbala’s municipalities were conducted during the event in 2016, to develop an overall picture of the municipal solid waste management system applied during the event. The data were analysed using thematic analysis and fed to the ‘Wasteaware’ benchmark indicators framework to evaluate the performance of the event system. The results indicated that the system suffers from operational and governance weaknesses. Despite a focus on municipal solid waste collection and transportation, the collection coverage is only ~ 70%. There is no controlled landfill site in Kerbala. It is estimated that currently ~ 5% of the event municipal solid waste is recycled by informal recyclers: there is no formal recycling scheme. Kerbala does not perform well regarding governance. The inclusivity of providers and users of the municipal solid waste management services is minimal during the event, as the majority of stakeholders are not included in decision-making processes. Municipal solid waste management services are delivered free of charge, thus significantly influencing the financial sustainability of the system. This study recommends that MSW recycling should be encouraged through integrating the informal sector, improving public awareness and introducing a formal recycling scheme to make the event municipal solid waste management system effective and financially sustainable

Benchmarking of the Current Solid Waste Management System in Karbala, Iraq, Using Wasteaware Benchmark Indicators

Solid waste management (SWM) poses severe problems to the authorities of the city of Kerbala, one of the main tourism centres in Iraq. Due to the city’s limited funds, it is crucial to evaluate the priorities for improvements in SWM services to tackle this problem efficiently. This paper employed Wasteaware benchmark indicators for integrated and sustainable solid waste management to evaluate the city SWM system performance. The data used in this evaluation was collected by in-depth interviews with the management authorities and field observations over two months in 2016. The outcomes showed that the SWM system in the city is weak. It therefore requires several improvements in physical infrastructure and management. Disposal and recycling were the highest priority to be improved among SWM physical components. While, in the management, the authority should have clear strategy for SWM and stakeholders such as public, private waste sector, and informal waste collectors should be included in SWM planning to improve the management services. This study can provide a starting point for the city authorities to prioritise their actions to improve the current SWM system

Chaos induced coherence in two independent food chains

Coherence evolution of two food web models can be obtained under the stirring effect of chaotic advection. Each food web model sustains a three--level trophic system composed of interacting predators, consumers and vegetation. These populations compete for a common limiting resource in open flows with chaotic advection dynamics. Here we show that two species (the top--predators) of different colonies chaotically advected by a jet--like flow can synchronize their evolution even without migration interaction. The evolution is charaterized as a phase synchronization. The phase differences (determined through the Hilbert transform) of the variables representing those species show a coherent evolution.Comment: 5 pages, 5 eps figures. Accepted for publication in Phys. Rev.

Three-dimensional virtual-reality surgical planning and soft-tissue prediction for orthognathic surgery

Complex maxillofacial malformations continue to present challenges in analysis and correction beyond modern technology. The purpose of this paper is to present a virtual-reality workbench for surgeons to perform virtual orthognathic surgical planning and soft-tissue prediction in three dimensions. A resulting surgical planning system, i.e., three-dimensional virtual-reality surgical-planning and soft-tissue prediction for orthognathic surgery, consists of four major stages: computed tomography (CT) data post-processing and reconstruction, three-dimensional (3-D) color facial soft-tissue model generation, virtual surgical planning and simulation, soft-tissue-change preoperative prediction. The surgical planning and simulation are based on a 3-D CT reconstructed bone model, whereas the soft-tissue prediction is based on color texture-mapped and individualized facial soft-tissue model. Our approach is able to provide a quantitative osteotomy-simulated bone model and prediction of postoperative appearance with photorealistic quality. The prediction appearance can be visualized from any arbitrary viewing point using a low-cost personal-computer-based system. This cost-effective solution can be easily adopted in any hospital for daily use.published_or_final_versio

Measurements, Models, Systems and Design

531 s.

Invasion speeds for structured populations in fluctuating environments

We live in a time where climate models predict future increases in environmental variability and biological invasions are becoming increasingly frequent. A key to developing effective responses to biological invasions in increasingly variable environments will be estimates of their rates of spatial spread and the associated uncertainty of these estimates. Using stochastic, stage-structured, integro-difference equation models, we show analytically that invasion speeds are asymptotically normally distributed with a variance that decreases in time. We apply our methods to a simple juvenile-adult model with stochastic variation in reproduction and an illustrative example with published data for the perennial herb, \emph{Calathea ovandensis}. These examples buttressed by additional analysis reveal that increased variability in vital rates simultaneously slow down invasions yet generate greater uncertainty about rates of spatial spread. Moreover, while temporal autocorrelations in vital rates inflate variability in invasion speeds, the effect of these autocorrelations on the average invasion speed can be positive or negative depending on life history traits and how well vital rates ``remember'' the past

Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models

Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process and a variant of the Eden model as special cases. We employ the concept of a "roughened" front to quantify effects of discreteness and stochasticity on invasion; we emphasize the probability distribution of the front-runner's relative position. That is, we analyze the location of the most advanced invader as the extreme deviation about the front's mean position. We find that a class of models with different assumptions about neighborhood interactions exhibit universal characteristics. That is, key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the invading front) to invasion velocity, and to the relative position of the most advanced invader.Comment: The original publication is available at www.springerlink.com/content/8528v8563r7u2742