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61.
The future of telecommunications is to reach mass population in all regions of the world with services that will benefit humankind leading to the betterment of its and all life in our planet. Telecommunications and its services have to and will become part of life as is breathing to mankind. This future is by far not achieved and for some time to come whatever we develop there is always a next step to it. After all, that keeps our world going.Currently we are again at that stage of work on future generation communications where these words have not yet achieved a consensus. In this paper let us look at the crystal ball and try to materialize at least in words what we see in it [1–20].We first define fourth generation (4G) communication system and beyond 3G (B3G). Then we look at the requirements for future generation communications from the perspective of the users, the operators, and the service providers. Next the technologies that should and are being developed to materialize the future generation are discussed. A dip is also taken into the ongoing standardization or pre-standardization efforts. At first the introduction section tries to raise questions on the “future”.Prof. Dr. Ramjee Prasad, while being a father always there for his children, is also a visionary and a leader in the field of telecommunications. It is with pride and honour that I write in this paper, on the occasion of 60th birthday of my father, my thoughts of the future of telecommunications. I owe to him and my mother the knowledge that I present and the future that I have written of. It is from the spark that they had put in me that this vision of future was created thus the title “the future re-visited”. Disclaimer: This paper reflects opinion of the author not of NTT DoCoMo or DoCoMo Euro-Labs. Anand Raghawa Prasad Senior Member IEEE, project manager network level security model group, DoCoMo Euro-Labs, Munich, Germany was born in Ranchi, India. He received his Ph.D. degree in the field of WLANs: protocols, security and deployment and MSc (Ir.) degree in the field of Self Similarity in ATM Network Traffic from Delft University of Technology, The Netherlands, in 2003 and 1996, respectively. From 1996 to 1998 he worked as research engineer and later project leader in Uniden Corporation, Tokyo, Japan. From 1998 to 2000, he was distinguished member of technical staff and worked as systems architect for IEEE 802.11 based WLANs (WaveLAN and ORiNOCO) in Lucent Technologies, Nieuwegein, The Netherlands. Subsequently, he was technical director at Genista Corporation, Tokyo, Japan, and technical advisor of PCOM:I3, Aalborg, Denmark. He was a voting member of IEEE 802.11 and he is an active participant of 3GPP. In addition to his publications in journals, international conferences and chapters in books, he has 20$+$ patent applications in the field of wireless communications and has co-edited a book titled “WLAN Systems and Wireless IP for Next Generation Communications” and co-authored a book on “Wireless LANs and Wireless IP: Security, Mobility, QoS and Mobile Network Integration” both published by Artech House in 2002 and 2005 respectively. He is writing a book on “Security in Wireless Networks and Mobile Platforms” to be published in August 2006. He has participated in organizing of various International Conferences including VTC, PIMRC and WPMC. He was a guest editor of a special issue on “Security for Next Generation Communications” of the Springer Journal on Wireless Personal Communications and he is a guest editor of a special issue on “Seamless Handover in Next Generation Wireless/Mobile Communications” of Wireless Personal Communications.  相似文献   
62.
Heterochromatin protein 1 (HP1) of Drosophila and its homologs in vertebrates are key components of constitutive heterochromatin. Here we provide cytological evidence for the presence of heterochromatin within a euchromatic chromosome arm by immunolocalization of HP1 to the site of a silenced transgene repeat array. The amount of HP1 associated with arrays in polytene chromosomes is correlated with the array size. Inverted transposons within an array or increased proximity of an array to blocks of naturally occurring heterochromatin may increase transgene silencing without increasing HP1 labeling. Less dense anti-HP1 labeling is found at transposon arrays in which there is no transgene silencing. The results indicate that HP1 targets the chromatin of transposon insertions and binds more densely at a site with repeated sequences susceptible to heterochromatin formation.  相似文献   
63.
Fifty consecutive cases of surgical instrumentation and fusion for adolescent idiopathic scoliosis were prospectively studied to test the hypothesis that the use of predonated autologous blood combined with judicious perioperative blood salvage could decrease the amount of homologous blood needed. All cases had posterior instrumentation and fusion. Nineteen patients had their rib prominence resected with an average of 4.8 ribs per patient. Our protocol called for perioperative blood salvage with the cell saver and reinfusion of postoperative drained blood if more than 300 ml were drained in 4 hours. Two units of predonated autologous blood was made available. Hypotensive anesthesia and meticulous hemostasis kept the blood loss to a minimum. The average total blood loss was 1,055 ml. Blood loss per segment was 91 ml with an average of 11 segments fused per patient. Patients with rib resection had a blood loss of 1,105 ml, while those without had a blood loss of 955 ml. The cell saver blood returned per case was 391 ml with the hematocrit of the product averaging 46%. Twelve patients were reinfused an average of 300 ml of the postoperative drained blood. The predonated autologous blood was used as part of the intraoperative fluid management. In no patient was homologous blood needed. The average starting hematocrit was 35.6%, with the hematocrit at discharge (seventh day) being 32.4%. There were no complications or blood transfusion reactions. Our results suggest that judicious perioperative blood management may decrease the need for homologous blood transfusion in selected posterior idiopathic scoliosis surgery.  相似文献   
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Anand  Y. Christou  A. Day  H. 《Electronics letters》1980,16(15):581-583
Refractory Schottky barriers have been incorporated in millimetre GaAs mixer diodes to improve r.f. performance and burnout resistance. It is shown that low power r.f. sputter deposition of TiW and Ti-Mo refractories results in degradation of noise temperature ratio and to a first approximation does not affect d.c. parameters, especially the ideality factor.  相似文献   
67.
D.K. Anand  I.N. Deif 《Energy》1979,4(4):537-548
System simulations for sizing and performance predictions of various solar systems require some form of weather input to act as a system stimulus. When actual weather data is used, hourly simulations are expensive and require considerable data handling. For many design procedures, however, hourly information is not needed, and simpler methods are desirable. One such method employs a probabilistic approach. This method involves the use of an algorithm that generates a probabilistic matrix, and an analytical formulation which is used to generate synthetic weather data. The approach has been found to be satisfactory. This work uses the stochastic (probablistic) method to produce representative weather for five geographic regions in the U.S. for the summer months. Parallel runs are conducted with real and stochastic weather. A comparison of the results clearly shows that the probabilistic approach can satisfactorily substitute for real weather for long-term system performance.  相似文献   
68.
Biomedical engineering has been recognized in India for the last decade. Technological developments have been in areas of importance to the country, with several groups actively involved in the promotion of bioengineering, particularly in New Delhi. A group at the National Physical Laboratory has contributed significantly to the field of ultrasonics as well as to the development of piezoelectric transducers for other biomedical uses. The Centre for Biomedical Engineering of the Indian Institute of Technology and the All India Institute of Medical Sciences is one of the country's leading centres producing outstanding work in areas like instrumentation, rehabilitation, biomaterials, modelling and analysis. Research in technology applied to reproductive physiology (an area especially relevant to India's needs) was initiated at this centre. Research at the School of Environmental Sciences, Jawaharlal Nehru University has elucidated the effects and mechanisms of the action of low-energy electromagnetic radiation and ultrasound on biological systems--in one of the school's projects the use of bone material for ultrasonic transducers and optical detectors was successfully demonstrated. A selected list of publications shows the wide spectrum of research carried out at these institutions.  相似文献   
69.
The Capacitated Arc Routing Problem (CARP) stands among the hardest combinatorial problems to solve or to find high quality solutions. This becomes even more true when dealing with large instances. This paper investigates methods to improve on lower and upper bounds of instances on graphs with over 200 vertices and 300 edges, dimensions that, today, can be considered of large scale. On the lower bound side, we propose to explore the speed of a dual ascent heuristic to generate capacity cuts. These cuts are next improved with a new exact separation enchained to the linear program resolution that follows the dual heuristic. On the upper bound, we implement a modified Iterated Local Search procedure to Capacitated Vehicle Routing Problem (CVRP) instances obtained by applying a transformation from the CARP original instances. Computational experiments were carried out on the set of large instances generated by Brandão and Eglese and also on the regular size sets. The experiments on the latter allow for evaluating the quality of the proposed solution approaches, while those on the former present improved lower and upper bounds for all instances of the corresponding set.  相似文献   
70.
Mesoscale eddies enhance the productivity in a stratified coastal environment by upwelling. The seas around the Andaman and Nicobar Islands have been found to have frequent mesoscale eddy activity. Commercial fishing grounds coincide with upwelling areas associated with cyclonic and anticyclonic eddies and also with areas between two adjacent eddies. There are different eddy zones supporting different types of fishing gears and fish. The current study aims at identifying the different zones of mesoscale eddies in the Andaman Sea and compares the productivity and fishing activity in each of them. Data collected from 454 commercial fishing trips in the Andaman Sea along with maps of sea level anomaly and Moderate Resolution Imaging Spectroradiometer (MODIS) global level 3 mapped thermal infrared (IR) daytime sea surface temperature (SST) from the Aqua and Terra satellites were used for the study. Known upwelling areas such as the periphery of anticyclonic and the core of cyclonic eddies showed higher catches in longlines, ring seines among the fishing gears, and among all the fish species groups. Downwelling areas such as the periphery of cyclonic and the core of anticyclonic eddies showed lower catches with ring seines and the fish species groups. Areas in between adjacent eddies were explored in this study and the fish captures in such areas were found to be different with types of fishing and the target fish group. The study shows results that link eddy activity with the performance of a fishery.  相似文献   
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