High Frequency Communication Network with Diversity: System Structure and Key Enabling Techniques

High frequency sky wave communication suffers from poor performance including poor link quality and low link success rate. To enhance performance, diversity technology is proposed in the high frequency communication network(HFCN) in this paper.First, we present the benefits and the challenges by introducing diversity technology into the existing HFCN. Secondly, to exploit the benefits fully and overcome the challenges, we propose a system structure suitable for deploying diversity technology in HFCN in large scale,based on the cloud radio access network and software defined network. Moreover, we present a general structure for the real-time updating frequency management system that plays a more important role especially when resource consuming(e.g., frequency) diversity technology is deployed. Thirdly, we investigate the key techniques enabling diversity technology deployment. Finally, we point out the future research directions to help the HFCN with diversity work more efficiently and intelligently.

Phylogenetic biogeography and taxonomy of disjunctly distributed bryophytes

More than 200 research papers on the molecular phylogeny and phylogenetic biogeography ofbryophytes have been published since the beginning of this millenium. These papers corroborated assumptions of a complex genetic structure of morphologically circumscribed bryophytes, and raised reservations against many morphologically justified species concepts, especially within the mosses. However, many molecular studies allowed for corrections and modifications of morphological classification schemes. Several studies reported that the phylogenetic structure of disjunctly distributed bryophyte species reflects their geographical ranges rather than morphological disparities. Molecular data led to new appraisals of distribution ranges and allowed for the reconstruction of refugia and migration routes. Intercontinental ranges of bryophytes are often caused by dispersal rather than geographical vicariance. Many distribution patterns of disjunct bryophytes are likely formed by processes such as short distance dispersal, rare long distance dispersal events, extinction, recolonization and diversification.

Research of Technology Readiness Assessment for Aerospace Projects

Two problems were found in recent applications of TRLs in aerospace projects.One is how to accurately evaluate the readiness level of a given technology in a project using the TRL scale.The other is how to deal with the diversity(different types) of technologies involved in an aerospace project.To solve these problems,a technology readiness assessment(TRA) method based on three maturity characteristics is established,and this method is adapted according to the features of different types of technologies.The proposed method has been successfully applied to aerospace projects and enables great effectiveness and accuracy in assessing new technologies.

A High-throughput Genomic Tool： Diversity Array Technology Complementary for Rice Genotyping

Diversity array technology （DART^TM） was a genotyping tool characterized gel-independent and high throughput. The main purpose of present study is to validate DArT for rice （Oryza sativa L.）genotyping in a high throughput manner. Technically, the main objective was to generate a rice general purpose gene pool, and optimize this genomic tool in order to evaluate rice germplasm genetic diversity. To achieve this, firstly, a generalpurpose DArT array was developed. Ten representatives from 24 varieties were hybridized with the general-purpose array to determine the informativeness of the clones printed on the array. The informative 1 152 clones were re-arrayed on a slide and used to fingerprint 17 of 24 germplasms. Hybridizing targets prepared from the germplasm to be assayed to the DNA array gave DNA fingerprints of germplasms. Raw data were normalized and transformed into binary data, which were then analyzed by using NTSYSpc （Numerical taxonomy system for cluster and ordination analysis, v. 2.02j） software package. The graphically displayed dendrogram derived from the array experimental data was matched with simple sequence repeats genotyping outline and varieties＇ pedigree deviation of the different varieties. Considering DArT is a sequence-independent genotyping approach, it will be applied in studies of the genetic diversity and the gene mapping of diverse of organisms, especially for those crops with less-developed molecular markers.

Diversity arrays technology (DArT) for studying the genetic polymorphism of flue-cured tobacco (Nicotiana tabacum)

Diversity arrays technology （DART） is a microarray-based marker system that achieves high throughput by reducing the complexity of the genome. A DArT chip has recently been developed for tobacco. In this study, we genotyped 267 flue-cured cultivars/landraces, including 121 Chinese accessions over five decades from widespread geographic regions in China, 103 from the Americas, and 43 other foreign cultivars, using the newly developed chip. Three hundred and thirty polymorphic DArT makers were selected and used for a phylogenetic analysis, which sug- gested that the 267 accessions could be classified into two subgroups, which could each be further divided into 2-4 sections. Eight elite cultivars, which account for 83% of the area of Chinese tobacco production, were all found in one subgroup. Two high-quality cultivars, HHDJY and Cuibil, were grouped together in one section, while six other high-yield cultivars were grouped into another section. The 330 DArT marker clones were sequenced and close to 95% of them are within non-repetitive regions. Finally, the implications of this study for Chinese flue-cured tobacco breeding and production programs were discussed.

Spatial diversity and combination technology using amplitude and phase weighting method for phase-coherent underwater acoustic communications

The UWA channel is characterized as a time-dispersive rapidly fading channel, which in addition exhibits Doppler instabilities and limited bandwidth. To eliminate inter- symbol interference caused by multipath propagation, spatial diversity equalization is the main technical means. The paper combines the passive phase conjugation and spatial processing to maximize the output array gain. It uses signal-to-noise-plus-interference to evaluate the quality of signals received at different channels. The amplitude of signal is weighted using Sigmoid function. Second order PLL can trace the phase variation caused by channel, so the signal can be accumulated in the same phase. The signals received at different channels need to be normal- ized. It adopts fractional-decision feedback diversity equalizer （FDFDE） and achieves diversity equalization by using different channel weighted coefficients. The simulation and lake trial data processing results show that, the optimized diversity receiving equalization algorithm can im- prove communication system＇s ability in tracking the change of underwater acoustic channel, offset the impact of multipath and noise and improve the performance of communication system. The performance of the communication receiving system is better than that of the equal gain combination. At the same time, the bit error rate （BER） reduces 1.8%.

THREE BAYS ESTUARY(BARNSTABLE,CAPE COD)WATERSHED RESTORATION PL AN:A GREEN INFRASTRUCTURE APPROACH

This paper presents an approach described as“non-traditional”for restoring water quality and ecosystem services that have been degraded as a result of excess nitrogen.It focuses on emerging technologies often referred to as green infrastructure.These technologies may provide cost effective alternatives to traditional,gray infrastructure such as sewering and is likely to provide significant co-benefits including the creation of local jobs,the preservation of real estate values,and habitat enhancement.The paper focuses on the Three Bays estuary on Cape Cod to illustrate the benefits and potential of green infrastructure technologies.The Three Bays estuary is presented as a case study and as a representative example of implementation of the broader Cape Cod Water Quality Management Plan Update(208 Plan Update)-a nationally-recognized watershed planning project designed to provide a pathway for the fifteen towns of Cape Cod to achieve compliance with Section 208 of the Clean Water Act.The Three Bays estuary and embayment system is a scenic Cape Cod bay that hosts sailing,kayaking,swimming and shellfishing and is located in the Town of Barnstable.It is comprised of three primary segments that include West Bay,North Bay and Cotuit Bay.Sub-systems include Prince Cove that flows into North Bay,the Narrows that flows between North Bay and Cotuit Bay and Eel Pond that flows into East Bay(see Figure 1).The Massachusetts Estuaries Project(MEP)is a state-sanctioned watershedmodeling project that assesses the conditions of the state’s estuaries and required restoration goals.Its technical report(2006)indicates that the water quality of the Three Bays system has resulted in seriously degraded to moderately degraded habitat.The system is listed as an impaired water body on the US Environmental Protection Agency(EPA)303d list of impaired waters.An approved Total Maximum Daily Load(TMDL)for nitrogen has been established for the embayment.This assessment is supported by more recent empirical water quality data collected within the embayment.The more current data documents a continuing decline in water quality with more common algae blooms(see Figure 2).

A Theoretical Method for Estimating Performance of Reed-Solomon Codes Concatenated with Orthogonal Space-Time Block Codes

Based on the studies of Reed-Solomon codes and orthogonalspace-time block codes over Rayleigh fading channel, a theoreticalmethod for estimating performance of Reed-Solomon codes concatenatedwith orthogonal space- time block codes is presented in this paper.And an upper bound of the bit error rate is also obtained. It isshown through computer simulations that the signal-to-noise ratioreduces about 15 dB or more after orthogonal space-time block codesare concatenate with Reed-Solomon(15,6)codes over Rayleigh fadingchannel, when the bit error rate is 10^-4.