277 research outputs found
STUDIES TOWARD SYNTHESIS OF POLYCYCLIC POLYPRENYLATED ACYLPHLOROGLUCINOLS
Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of compounds that reveal intriguing biological activities and interesting and challenging chemical structures. These products are claimed to possess antioxidant, antiviral, and antimitotic properties. Increasing interest is related to their function in the CNS as modulators of neurotransmitters associated to neuronal damaging and depression. All these features make PPAPs targets for synthesis. We decided to focus our own initial efforts in this area on the type A PPAP, nemorosone because we thought that its fairly simple structure relative to other PPAPs would present fewer hurdles as we developed our methodology.In the past decade many approaches to the synthesis of the bicyclo[3.3.1]nonane-2,4,9-trione structure of type A PPAPs have been reported, but only two total syntheses of any PPAP, garsubellin A by Shibasaki and Danishefsky, have been published recently, near the end of 2005. All approaches have relied on the ??,????-annulation of a three-carbon bridge onto a cyclohexanone, although the methods used to execute this annulation differ dramatically. The methods most often used to form the two new C–C bonds have involved classical carbonyl chemistry.We have developed a short and efficient synthetic approach to the bicyclo[3.3.1]nonane skeleton of the PPAPs that involves a novel three-carbon ??,????-annulation of a sterically hindered cyclic ??-keto ester with 3,3-diethoxypropyne. The alkynylation reaction permits the construction of the two contiguous quaternary centers of the PPAPs in reasonable yield and without complications from side reactions. We have also successfully applied a recently developed syn hydrosilylation to the very hindered product of this alkynylation reaction. Our methodology received positive feedback already, and we see this total synthesis of nemorone as an ideal platform for the implementation of new synthetic methodologies
The notion of “SERVICES” in modern economy
The notion of “service” is a very important one, with an increasing role in an expanding economy which becomes the condition of sustainable and long-term development. The technical services that must be assured differ according to the type of product. In Romania, the market economy towards which we are moving today is characterized by an abundant production, an intensive national and foreign competition, a supplying facility all over the region. Through their decisions, consumers and users direct production, encouraging thus distributors through their forms of distribution. In all companies the commercial function includes a series of activities that concentrate on "obtaining an optimal market quota, achieving benefits indispensable for an efficient activity, and meeting consumers and users' requirements ". This conception identifies with the marketing one, and the services become an integral part of the dynamics that characterizes the actions which complete the proper commercial administration. The company must pay much attention to all these, the services being considered successful facts and elements that generate actions which must be included in activities such as selling, advertising and promoting.marketing, service, client
Reorganizing the Foreign Markets Portofolio, Part of the Company's Competitive Strategy
At the basis of the analysis of potential markets stands the business policy of the firm. Company’s managers are the ones who decide which markets it will serve, according to the vision, mission and business philosophy of the company. Relevant markets of the company are usually found in a number of countries. The evaluation of the most attractive national market will depend on the company's major objectives and also on its priorities. Objectives considered for selection may include: growth and stability, recovery of investment, market share, the acceptable risk level, the way of approaching technology and innovation, brand image, independence and cooperation as general approach of business.competitive strategies, foreign market selection, firm’s market portfolio, internationalization.
To know and satisfy tourist clients’ needs – a premise for achieving superior quality services
Clients’ satisfaction should be the main objective of any tourist company, and this involves a good knowledge of consumers’ expectations. Offering a high quality service is obviously based on fulfilling some requirements through which the service touches the level desired by the consumer. Knowing the consumers’ needs and expectations, as well as the perceptions related to the supplied service, should represent the quality management objectives of the services provided, that is, the conditions of providing performing tourist services. The tourist orientation can assure a high level of satisfaction and it involves the identification of his desires and requirements with regard to the services offered, his proper informing, facilities and possibilities to choose the service that corresponds the best to his expectations. In order to win the clients’ trust in the services offered – modifying the clients area of tolerance (that is, to enlarge it) the trained staff of service companies should be more sensitive to the clients needs, suggestions, dissatisfactions and preoccupations. A highly important condition for achieving the objectives of satisfying clients is the service company employees’ satisfaction. The trained staff is responsible to offer high quality services and satisfaction to the consumer, the latter’s behavior being able to increase or decrease the name of the service company. The staff’s efficient leading objective – and of the service offering process – can be achieved by a successful practicing of internal marketing, that has in view developing the staff motivation and its stimulation in the effort to offer high quality services. The fundamental strategy of internal marketing is to form faithful clients from its own employees. Satisfying internal clients’ requirements, the service company increases its ability to satisfy successfully external consumers’ needs.tourist, client, service
Evoluţii şi semnificaţii ale operaţiunilor de franchising pe plan naţional şi internaţional
The contents of this paper I will try to address all those interested in studying the system of franchising, both theoreticians and practitioners in this field to contribute to the progress of this system in our country. Franchising is a reality in motion which will write more, being on time to find a theoretical foundation able to provide solutions for all aspects and economic instruments involved a commercial phenomenon. Novelty apparent basis of: • importance and the complexity and variety of system franchise (franchise), but at the same time very interesting and appropriate, the pace with this growing vertical marketing system and contract in the world economy; • that specialized in Romanian literature is not enough work to deal with the franchise system as a whole broad issue of the whole system; • theoretical and practical knowledge in this area are generally poor in our country, for development imposed by the very nature deeply International franchise system; • deeply democratic franchise system in terms of organization, where relations between franchisors and franchisees are partnership firms having independent franchisees legal and financial part to ensure a more cooperative advantage superior to other systems in the world economy; • by expanding the franchise system existence and create new jobs, promoting and strengthening the middle class society of a country; • universal economic reality created the concept of globalization to achieve world number one organizational system. One of the major systems of vertical organization and service area is considered disposal and franchise system, widely practiced in contemporary economy; • this system can join with small steps between the pillars of economic and financial stability of the new millennium. The success of franchises is most dependent on one man: the franchisee, and to be successful is not enough that it will have the necessary knowledge to purchase a license and to build a franchise unit, to arrange and start businesses in within this unit. Franchisee must be dedicated to his work, it must have the desire and willingness to work hard and ability to remain motivated, ability to do business.franchising, business, evolution, strategy
Multiuser Downlink Beamforming Techniques for Cognitive Radio Networks
Spectrum expansion and a significant network densification are key elements in meeting the ever increasing demands in data rates and traffic loads of future communication systems. In this context, cognitive radio (CR) techniques, which sense and opportunistically use spectrum resources, as well as beamforming methods, which increase spectral efficiency by exploiting spatial dimensions, are particularly promising. Thus, the scope of this thesis is to propose efficient downlink (DL) beamforming and power allocation schemes, in a CR framework. The methods developed here, can be further applied to various practical scenarios such as hierarchical multi-tier, heterogenous or dense networks. In this work, the particular CR underlay paradigm is considered, according to which, secondary users (SUs) opportunistically use the spectrum held by primary users (PUs), without disturbing the operation of the latter. Developing beamforming algorithms, in this scenario, requires that channel state information (CSI) from both SUs and PUs is required at the BS. Since in CR networks PUs have typically limited or no cooperation with the SUs, we particularly focus
on designing beamforming schemes based on statistical CSI, which can be obtained with limited or no feedback. To further meet the energy efficiency requirements, the proposed beamforming designs aim to minimize the transmitted power at the BS, which serves SUs at their desired Quality-of-Service (QoS), in form of Signal-to-interference-plus-noise (SINR), while respecting the interference requirements of the primary network.
In the first stage, this problem is considered under the assumption of perfect CSI of both SUs and PUs. The difficulty of this problem consists on one hand, in its non-convexity and, on the other hand, in the fact that the beamformers are coupled in all constraints. State-of-the-art approaches are based on convex approximations, given by semidefinite relaxation (SDR) methods, and suffer from large computational complexity per iteration, as well as the drawback that optimal beamformers cannot always be retrieved from the obtained solutions.
The approach, proposed in this thesis, aims to overcome these limitations by exploiting the structure of the problem. We show that the original downlink problem can be equivalently
represented in a so called ’virtual’ uplink domain (VUL), where the beamformers and powers are allocated, such that uplink SINR constraints of the SUs are satisfied, while both SUs and PUs transmit to the BS. The resulting VUL problem has a simpler structure than the original formulation, as the beamformers are decoupled in the SINR constraints. This allows us to develop algorithms, which solve the original problem, with significantly less computational complexity than the state-of-the-art methods. The rigurous analysis of the Lagrange duality, performed next, exposes scenarios, in which the equivalence between VUL and DL problems can be theroretically proven and shows the relation between the obtained powers in the VUL domain and the optimal Lagrange multipliers, corresponding to the original problem.
We further use the duality results and the intuition of the VUL reformulation, in the extended problem of joint admission control and beamforming. The aim of this is to find a maximal set of SUs, which can be jointly served, as well as the corresponding beamforming and power allocation. Our approach uses Lagrange duality, to detect infeasible cases and the intuition of the VUL reformulation to decide upon the users, which have the largest
contribution to the infeasibiity of the problem. With these elements, we construct a deflation based algorithm for the joint beamforming and admission control problem, which benefits from low complexity, yet close to optimal perfomance. To make the method also suitable for dense networks, with a large number of SUs and PUs, a cluster aided approach is further proposed and consists in grouping users, based on their long term spatial signatures.
The information in the clusters serves as an initial indication of the SUs which cannot be simultaneously served and the PUs which pose similar interference constraints to the BS.
Thus, the cluster information can be used to significantly reduce the dimension of the problem in scenarios with large number of SUs and PUs, and this fact is further validated by extensive simulations.
In the second part of this thesis, the practical case of imperfect covariance based CSI, available at the transmitter, is considered. To account for the uncertainty in the channel knowledge, a worst case approach is taken, in which the SINR and the interference
constraints are considered for all CSI mismatches in a predefined set One important factor, which influences the performance of the worst case beamforming approach is a proper choice of the the defined uncertainty set, to accurately model the possible uncertainties in the CSI.
In this thesis, we show that recently derived Riemannian distances are better suited to measure the mismatches in the statistical CSI than the commonly used Frobenius norms, as they better capture the properties of the covariance matrices, than the latter. Therefore,
we formulate a novel worst case robust beamforming problem, in which the uncertainty set is bounded based on these measures and for this, we derive a convex approximation, to which a solution can be efficiently found in polynomial time. Theoretical and numerical results confirm the significantly better performance of our proposed methods, as compared to the state-of-the-art methods, in which Frobenius norms are used to bound the mismatches.
The consistently better results of the designs utilizing Riemannian distances also manifest in scenarios with large number of users, where admission control techniques must supplement
the beamforming design with imperfect CSI. Both benchmark methods as well as low complexity techniques, developed in this thesis to solve this problem, show that designs based on Riemannian distance outperform their competitors, in both required transmit power as
well as number of users, which can be simultaneously served
Probabilistic Ray-Tracing Aided Positioning at mmWave frequencies
We consider the following positioning problem where several base stations
(BS) try to locate a user equipment (UE): The UE sends a positioning signal to
several BS. Each BS performs Angle of Arrival (AoA) measurements on the
received signal. These AoA measurements as well as a 3D model of the
environment are then used to locate the UE. We propose a method to exploit not
only the geometrical characteristics of the environment by a ray-tracing
simulation, but also the statistical characteristics of the measurements to
enhance the positioning accuracy.Comment: Accepted at the conference Indoor Positioning and Indoor Navigation
(IPIN) 202
Nonlinearity Correction Algorithm for Wideband FMCW Radars
International audienceThis paper presents a novel nonlinearity correction algorithm for wideband frequency modulated continuous wave (FMCW) radars based on high-order ambiguity functions (HAF) and time resampling. By emphasizing the polynomial phase nature of the FMCW signal, it is shown that the HAF is an excellent tool for estimating the sweep nonlinearity polynomial coefficients. The estimated coefficients are used to build a correction function which is applied to the beat signal by time resampling . The nonlinearity correction algorithm is tested by simulation and validated on real data sets acquired with an X-band FMCW radar
Analyse et traduction en italien de La traduction est une histoire d’amour de Jacques Poulin
L’œuvre qui fait l’objet du présent mémoire est La traduction est une histoire d’amour de Jacques Poulin. Le mémoire est divisé en deux parties. La première partie est elle-même divisée en trois sections. La première section présente de manière générale l’auteur et l’œuvre. La deuxième section présente les problématiques concernant la traduction d’une œuvre québécoise en Italie. On y trouve une analyse de la littérature québécoise et de son accueil dans une culture différente. Dans la même section, on présente l’approche traductive dans sa dimension théorique en analysant deux œuvres importantes : Dire presque la même chose d’Umberto Eco et La traduction et la lettre ou l’auberge du lointain d’Antoine Berman. Ces œuvres sont importantes pour le mémoire car ces deux auteurs présentent deux approches différentes mais en même temps connexes et d’une certaine façon complémentaires. Le parti pris du présent mémoire est de trouver une voie entre les deux. Dans la même section, on analyse les idées sur la traduction exprimées par Poulin et la figure du traducteur dans ses œuvres.
Dans la troisième section, se trouve la présentation de la méthodologie. Dans cette section, on traite des difficultés propres au transfert linguistique et culturel de La traduction est une histoire d’amour. En connexion avec ces dernières, on analyse le style de Poulin et les thématiques dans ses œuvres. Cette section est très importante car on explique les choix faits dans la traduction de l’œuvre.
La deuxième partie du mémoire est constituée de la traduction au complet de La traduction est une histoire d’amour de Jacques Poulin.Abstract : The novel at the center of this M.A. thesis is La traduction est une histoire
d’amour, by Jacques Poulin. The thesis is divided into two main parts. The
first part is divided into three sections. The first section gives a general
presentation of the author and his work. The second section presents the
difficulties connected to the translation of a Québécois work in the Italian
culture. There is an analysis of that literature as it is transferred into a different
culture, in this case the Italian one. In the same section is presented the
translation approach in its theoretical dimension; two important works are
analyzed: Dire presque la même chose by Umberto Eco and La traduction et
la lettre ou l’auberge du lointain by Antoine Berman. Both works are important
for the thesis because the authors present two different translation
approaches but at the same time their ideas are connected and, in a certain
way, complement one another. This M.A. thesis aims to find the middle
ground between these two approaches. In the same section are also
presented Poulin’s ideas about translation and the translator figure in his
work.
The third section deals with the methodology. In this section is presented the
analysis of difficulties concerning the linguistic and cultural transfer of La
traduction est une histoire d’amour. Connected to these, one finds the
analysis of Poulin’s style and themes present in his works. This section is very
important because I explain the choices made concerning the translation.
The second part of the thesis is comprised of the complete translation of
Jacques Poulin’s La traduction est une histoire d’amour
Short-Range FMCW Radar Platform for Millimetric Displacements Measurement
International audienceA frequency modulated continuous wave (FMCW) radar platform for millimetric displacement measurements of short-range targets is presented in this paper. The platform's transceiver is based on a heterodyne architecture because the beat frequency is relatively small for short-range targets and it can be placed in the frequency range influenced by the specific homodyne architecture problems: DC offset, self-mixing and 1/f noise. The platform's displacement measurement capability was tested on range profiles and SAR images acquired for various targets. The displacements were computed from the interferometric phase. The displacements errors were situated below 0.1 mm for metallic bar targets placed at a few meters from the radar
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