2,682 research outputs found
Using of Residual Number System as a Mathematical Basis for Software Defined Radio
Вступ. У традицiйному виглядi, програмно-визначена радiосистема (Software Defined Radio,
SDR) являє собою обчислювальне ядро, обладнане
приймально-передавальними блоками. З метою прискорення обчислювальних операцiй у системах SDR,
пропонується у якостi математичної основи застосування системи залишкових класiв. Результати попереднiх
дослiджень, що проводились рiзними групами вчених
з метою пошукiв шляхiв пiдвищення продуктивностi
обчислювальних засобiв, методiв органiзацiї ефективної
системи виявлення та виправлення помилок, а також
побудови надiйних обчислювальних комплексiв, дають
можливiсть стверджувати, що в межах позицiйних
систем числення не можна очiкувати принципових
зрушень в даних напрямках без суттєвого збiльшення робочих частот i ускладнення апаратної частини.
Перевагою пропонованого методу є те, що програмна
радiосистема може складатися з декiлькох ПЛIС i
обслуговувати декiлька незалежних радiоканалiв, а
перепрограмування властивостей дозволяє змiнювати число i складовi процесу обробки повiдомлень в
залежностi вiд поточних умов роботи.
Метод дослiдження. В роздiлi проаналiзовано паралельнiсть арифметичнi операцiї у системi залишкових
класiв. Цi операцiї називаються модульними, оскiльки
для обробки числових значень використовують невеликi
залишки дiлення на певний набiр модулiв, а для додавання i множення потрiбно лише один тактовий цикл
роботи обчислювальної системи. Для перетворення чисел iз двiйкової системи у RNS використовується алгоритм, заснований на застосуваннi китайської теореми
про залишки. Проте такi операцiї, як подiл, порiвняння
двох чисел i виявлення знака, є складними i ресурсо-затратними в RNS. Для цих проблемних операцiй було
запропоновано кiлька рiшень. Вони полягають у вiдсутностi процесу перетвореннi залишку в бiнарну систему
(зворотне перетворення) шляхом застосування цифро-аналогових перетворювачiв у RNS. З iншого боку, вибiр
правильного набору модулiв є ще одним важливим питанням для побудови ефективного RNS з достатнiм
динамiчним дiапазоном.
Результати та аналiз. Пiдводячи пiдсумки деяких
результатiв, можна зазначити, що система класiв залишкiв дозволяє значно полiпшити параметри обчислювача у SDR, а особливо у функцiональному блоковi Direct
Digital Synthesizers (DDS) у порiвняннi з обчислювачем,
побудованим на тiй же фiзичнiй i технологiчнiй основi, але в позицiйнiй обчислювальнiй системi, а також
отримання нових бiльш прогресивних конструктивних
i структурних рiшень. Експериментальнi результати показують, що представленi методи дають значнi переваги
для цифрових фiльтрiв у SDR, якi характеризуються
високим динамiчним дiапазоном i мають велику кiлькiстю ланок, особливо коли повнi перемножувачi не
доступнi у цiльовiй архiтектурi FPGA, або коли цi перемножувачi повиннi використовуватися для рiзних цiлей.
Висновки. Таким чином, запропонована система
вносить явнi переваги перед iснуючими системами i показує переваги продуктивностi обчислювальних операцiй i може бути використана для побудови сучасних систем зв’язку. Запропонована архiтектура зменшує розмiри конвеєру суматорiв i перемножувачiв, що є дуже
важливим фактором при розробцi високошвидкiсних
SDR.Introduction. In the classic view, program-defined radio system (Software Defined Radio, SDR) is a central
processor, equipped with receiving and transmitting units. In order to speed up computational operations
in SDR systems it is proposed to use the system of residual classes as a mathematical basis. The results
of research conducted by various groups of scientists in order to find ways to improve the performance of
computing tools, methods of organizing an effective system for detecting and correcting errors, as well as
building reliable computer systems, make it possible to assert that, within the limits of positional number
systems, no fundamental changes can be expected in these areas without a significant increase in operating
frequencies and hardware complications. The advantage of this method is that a software radio system can
consist of several FPGAs and serve several independent radio channels, and reprogramming the properties
allows you to change the number and components of message processors depending on current operating
conditions.
Research method. The equations in this section show the parallel nature of the RNS, free from bit
transfers. These operations are called modular, because for it takes only one clock cycle to process the
numerical values. To convert numbers from the binary position number system to RNS we use an algorithm
based on the application of a distributed arithmetic. However, operations such as division, comparison of two
numbers, and the detection of a sign are laborious and expensive in RNS Several decisions were proposed for
these problem operations. They consist in the absence of the process of converting a residue into a binary
system (reverse transformation) by using digital-to-analog converters in RNS. On the other hand, choosing
the right set of modules is another important issue for building an effective RNS with a sufficient dynamic
range.
Results and analysis. Summing up some results, it can be noted that the system of residual classes allows
to significantly improve the parameters of a computer in SDR especially in functional block a Direct Digital
Synthesizers (DDS) in comparison with a computer built on the same physical and technological basis, but
in a positional system calculation, and also to receive new more progressive constructive and structural
solutions. The experimental results shows that the presented techniques offer interesting advantages for FIR
filters characterized by high dynamic range and high number of taps especially when full custom multipliers
are not available in the target FPGA architecture or when they must to be used for different purposes.
Conclusion. Thus, the proposed system introduces clear advantages over existing systems and shows
performance advantages and can be used to build modern communication systems. The proposed architecture
reduces the size of the pipeline adders and multipliers which is a very important factor in the design SDR
for fast work.В статье рассмотрены принципы построения и функционирования систем, определенных программным
обеспечением (Software Defned Radio, SDR). С целью
ускорения вычислительных операций в системах SDR
предлагается применение системы остаточных классов в качестве математической основы построения систем. Преимуществом приведенного метода является
то, что программная радиосистема может состоять из
нескольких ПЛИС и обслуживать несколько независимых радиоканалов, а перепрограммирование свойств
позволяет изменять число и составляющие процессоры
сообщений в зависимости от текущих условий роботы.
Приведены проблемы формирования выходного сигнала. Описаны особенности внедрения операций прямого
и обратного преобразований с позиционных на непозиционые системы исчисления. Рассмотрена структурная
модель SDR с прямыми цифровыми синтезаторами частоты, ЦАП, АЦП, цифровыми фильтрами в системе
остаточных классов. Рассмотрены методы преобразования системы остаточных класов в аналоговый сигнал.
Рассматриваются проблемы эффективного использования площади кристалла для SDR и уменьшения задержек в формировании выходного сигнала. Полученные
результаты показывают широкие возможности применения программно определенной радиосистемы в системе остаточных классов
Organizational model of the congress and exhibition cluster in the field of business travel
The relevance of the analyzed issue is caused by the growth of the international trade in the intensity of business travel services, including in the field of the congress and exhibition business, which necessitates the formation of the effective management model of business travel services at the destination level. The purpose of the article is to substantiate the formation algorithm of the cluster development strategy of tourism and the development of organizational functioning models of the congress and exhibition cluster in the destination. The leading approach to the study of this issue is the method of modeling, which allowed considering the practice of clusters functioning as a sequence of stages of its formation and development, taking into account the resource potential of destinations. Results: the article presents a stepwise algorithm for creating the congress and exhibition cluster in the destination and proves the fundamental organizational model for its functioning in the business tourism market; isolates and systematized criteria and indicators for assessing the contribution of participants of the tourism cluster in the destination development. The contents of this article may be useful for researchers, interested in the use of the cluster approach in the services sector, as well as to regional authorities, responsible for the development of tourism. © 2016 Karpova et al
Prerequisites for setting up management system in municipal retail trade
The relevance of the problem is determined by the number of complex problems that exist in present Samara municipal retail trade system, which is manifested in the lack of regulation, a glut of sales area, poorly developed infrastructure. The purpose of this article is to form a quantitative base for determining the municipal needs in the floor space. Leading method to study this problem is the method of empirical observations and mathematical modeling. The study results: the article contains the analysis of sales area availability on the example in the urban district and presents a quantitative method to determine predictive values for retail trade turnover. Practical significance: the paper is aimed to develop managerial decisions in the sphere of municipal trade regulation. © 2016 Suraeva et al
Biological diversity of the coastal zone of the Crimean peninsula: problems, preservation and restoration pathways
The results of complex hydrochemical, hydrobiological and ichthyological investigations by IBSS, NAS of Ukraine, realized in 6 regions of the coastal zone of the Crimean peninsula in the Black Sea and the Sea of Azov are given. The main negative factors causing changes in structural and functional characteristics of hydrobiocenoses in the regions studied are analyzed and “hot ecological spots” are isolated. Variants of different methods of management of the coastal ecosystems, including construction of artificial reefs and usage of biological filters for water cleaning, protection and recreation of biological diversity are taken into consideration
Input of Congress-Exhibition Services to the Economy of a Destination: Development of Assessment Methodology
Quantitative indicators of tourism development are presented: direct and common input of tourism to the global GDP, influence of the touristic sphere on employment and investment activity in 2015–2017. General approaches of tourism contribution evaluation to the destination’s economy are systematized. They are analyzed in the context of applicability in the meetings industry. In order to develop methodological system of evaluation of the congress-exhibition contribution to the destination development, set of indicators is proposed. It includes four basic groups with certain valuation factors: group of economical and social factors, group of connected with destination promotion to the national and world markets, group of business-factors, and group of research intensity factors of a destination’s industry sectors
Difficulties in diagnosis and treatment of adult-onset Still's disease concurrent with pericardial effusion as a leading clinical manifestation
The paper considers a case of adult-onset Still's disease that occurred as acute pericarditis, two-spike hectic fever, and neutrophilic leukocytosis in a young man. It was difficult to establish a correct diagnosis because there were no characteristic clinical symptoms of Still's disease, such as salmon colored rash, arthralgia, and sore throat. The diagnosis of adult-onset Still's disease was verified on the basis of the classification criteria described by M. Yamaguchi et al. The special feature of the clinical case was the development of steroid resistance and the effective use of a combination of the interleukin-6 receptor blocker tocilizumab (8 mg/kg body weight, given intravenously dropwise once every four weeks) and methotrexate (15 mg/week orally). During this treatment, a sustained clinical and laboratory response was achieved, which could reduce the dose of glucocorticoids to the maintaining one
ABOUT THE CIRCULATION OF INFLUENZA VIRUS A AND THE DEATHS OF BIRDS IN SOUTH OF CENTRAL SIBERIA
It was studied the long-term dynamics of influenza A viruses circulation in the Southern Central Siberia. Also, we studied of birds population dynamic as the main carriers of viral infection, as well as spatial and temporal distribution of positive samples containing specific antibody to influenza viruses subtypes H5 and. H7 and. genomic RNA of these subtypes. It was considered the cases of mortality wild. and. synanthropic birds in the region. It was shown a correlation between the identified centers of the virus influenza, the deaths of birds and. human disease with significant excess seasonal epidemic threshold, including a subtype Н1NЫЦ
Role of Fractals in Perovskite Solar Cells
The interface engineering plays important role in fabrication of the tandem and perovskite based solar cells. Recent experiments show that the interface effects caused by the coupling of the electron bands and the pairing of geometry of contacting surfaces. In particular, it has been experimentally revealed that the transition from planar to the rough interface improves many photoelectric parameters of the device. It means that the value of the fractal dimension of the interface may be key factor in device performance. It is possible to formulate two problems: firstly, the understanding on simple models why the electrical properties at fractal interfaces are improved, and, secondly, to discuss one of the most promising approaches in modern electronics, namely technology of radiation applications in the creation of rough interfaces. Thirdly, the problem of photodegradation is analyzed in detail in the structures containing the fractal interfaces. On the basis of the constructed models, it was found: i) increase of roughness (fractal) of interface structure can enhance the role of total internal light reflection effect, thereby increasing the effective light path, and therefore, the number of generated e-h-pairs; ii) the curvature of the surface leads to the shift of Tamm levels both to the borders of allowed bands, and to the middle of the band gap; it opens the way of the control of carrier recombination on the interface; iii) surface Tamm orbitals interact differently each with other on the convex and concave areas; it leads to the different probability of defect formation and, consequently, reduces the fractal interface, inhibiting the effect of increasing of the photocurrent associated with the fractal interface (new channel of photodegradation)
Hypoxia-induced factor-1α and markers of inflammation in patients with ischemic stroke
Ischemic stroke (IS) occurs as a result of local disturbance of hemocirculation and hypoxia in the brain tissue. Hypoxia-inducible factor-1α (HIF-1α), which is involved in the regulation of tissue oxygen levels, plays an important role in the pathophysiology of stroke, including neuronal survival, neuroinflammation, angiogenesis, glucose metabolism, blood-brain barrier permeability, and is important in IS outcomes. The purpose of the study was to determine the relationship between blood levels of HIF-1α and the degree of neurological deficit in the acute period of IS and the outcome of the disease. We examined 58 people with IS aged 73 (67-81) years. Patients were divided into two groups – discharged and dead. The severity of stroke (NIHSS), neurological deficit, comorbidity index, blood levels of HIF-1α, p53 protein, interleukin-6, cystatin C, CRP, creatinine, hematological parameters were determined at admission, on days 3 and 10 of the disease. At admission the blood levels of HIF-1α was lower than in the comparison group and remained reduced until the 10th day. On day 10 the association of HIF-1α with neurological deficit, comorbidity index and disease outcome was determined. We observed a feedback of HIF-1α with the content of erythrocytes, hemoglobin and hematocrit, which can be regarded as a reflection of the hemic component of mixed hypoxia. In dead patients, an increased blood level of cystatin C was detected, which was associated with HIF-1α concentrations. In all periods of observation of IS, a correlation between cystatin C and creatinine and CRP levels was noted. These results may indicate dysfunction of endotheliocytes, inflammation associated with hypoxia in IS. The prognostic significance of the blood level of HIF-1α on the 10th day for the outcome of IS was AUC = 0.900. Blood levels of HIF-1α in the acute period was associated with the severity of IS and the outcome of the disease
Steady-frequency waves at intradiurnal periods from simultaneous co-located microbarometer and seismometer measurements: a case study
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