Based on the frequency domain training sequences, the polynomial-based carrier frequency offset （CFO） estimation in multiple-input multiple-output （ MIMO ） orthogonal frequency division multiplexing （ OFDM ） sys...Based on the frequency domain training sequences, the polynomial-based carrier frequency offset （CFO） estimation in multiple-input multiple-output （ MIMO ） orthogonal frequency division multiplexing （ OFDM ） systems is extensively investigated. By designing the training sequences to meet certain conditions and exploiting the Hermitian and real symmetric properties of the corresponding matrices, it is found that the roots of the polynomials corresponding to the cost functions are pairwise and that both meger CFO and fractional CFO can be estimated by the direct polynomial rooting approach. By analyzing the polynomials corresponding to the cost functions and their derivatives, it is shown that they have a common polynomial factor and the former can be expressed in a quadratic form of the common polynomial factor. Analytical results further reveal that the derivative polynomial rooting approach is equivalent to the direct one in estimation at the same signal-to-noise ratio（SNR） value and that the latter is superior to the former in complexity. Simulation results agree well with analytical results.展开更多
A layered algorithm by bidirectional searching is proposed in this paper to solve the problem that it is difficult and time consuming to reach an optimal solution of the route search with multiple parameter restrictio...A layered algorithm by bidirectional searching is proposed in this paper to solve the problem that it is difficult and time consuming to reach an optimal solution of the route search with multiple parameter restrictions for good quality of service. Firstly, a set of reachable paths to each intermediate node from the source node and the sink node based on adjacent matrix transformation are calculated respectively. Then a temporal optimal path is selected by adopting the proposed heuristic method according to a non-linear cost function. When the total number of the accumulated nodes by bidirectional searching reaches n-2, the paths from two directions to an intermediate node should be combined and several paths via different nodes from the source node to the sink node can be obtained, then an optimal path in the whole set of paths can be taken as the output route. Some simulation examples are included to show the effectiveness and efficiency of the proposed method. In addition, the proposed algorithm can be implemented with parallel computation and thus, the new algorithm has better performance in time complexity than other algorithms. Mathematical analysis indicates that the maximum complexity in time, based on parallel computation, is the same as the polynomial complexity of O(kn2-3kn+k), and some simulation results are shown to support this analysis.展开更多
As far as we are concemed, one of the elements of assessing EFL/ESL （English as a Foreign Language/English as a Second Language） learners＇ language proficiency in institutions and universities in our country ＂lran...As far as we are concemed, one of the elements of assessing EFL/ESL （English as a Foreign Language/English as a Second Language） learners＇ language proficiency in institutions and universities in our country ＂lran＂ are multiple-choice reading comprehension tests. We also know that, it comprises one major section of the standard and TOEFL （Test of English as a Foreign Language） tests. Taking into account its importance and the problems which EFL learners have answered them, I get motivated to uncover some of the test-taking strategies which they employ to answer multiple-choice reading comprehension questions when dealing with familiar versus unfamiliar topics. To get a better conclusion, I choose 20 advanced male and female candidates whose English proficiency is at an acceptable level and at least at the same age level, and they major in English language from different colleges and universities. They are given two reading comprehension passages （familiar and unfamiliar）, each one with five final questions and allotted time to answer the questions. Two main instruments in this study are a retrospective think-aloud protocol and a semi-structured interview. The results of the reading comprehension tests and interview part revealed that advanced learners＇ high scores in the familiar topic were not because of their strategy use but because of their high linguistic and background knowledge on the topic. I also concluded that the number, kind, and sequence of strategies employed, were greatly dependent on the degree of testees＇ familiarity on the topic. In other words, test-takers used more strategies to compensate for their lack of linguistic knowledge.展开更多
Six types of termites＇ baits （cartoon, rough tissues, soft toilet tissues, acacia wood, saw dust of building wood and sackcloth） were elicited variable degree of attraction toward Anacanthotermes ochaceus, where th...Six types of termites＇ baits （cartoon, rough tissues, soft toilet tissues, acacia wood, saw dust of building wood and sackcloth） were elicited variable degree of attraction toward Anacanthotermes ochaceus, where the best one was cardboard, followed by soft and rough toilet tissue at mono-choice and multiple-choice tests. Chemical analysis showed that there were variations in the chemical constituents （lignin, cellulose, N, H and C） of the six baits studied. On the other hand, olfactory reactions of harvester termites toward eight volatile oils （four natural medical plants and four commercial terpines） were repellent, but the most repellent one was cineol and the least one was clove oil. The most tested oils were caused inhibition in feeding, except cedar wood. The most toxic oils were cineol followed by thymol.展开更多
This paper deals with the importance of idioms in English as a Foreign Language （EFL） acquisition in general and the effect of three techniques applied in teaching and learning them by the undergraduate university s...This paper deals with the importance of idioms in English as a Foreign Language （EFL） acquisition in general and the effect of three techniques applied in teaching and learning them by the undergraduate university students in particular. To accomplish this aim, the study firstly tried to investigate English students＇ attitude toward learning L2 idioms through a 10-item questionnaire. The second part of the study passed on two stages; a list of 20 unknown idioms was presented to 30 second-year EFL students who were divided into three groups. The first group of students was given the list of idioms with （L2） English definition; the second group was given the same list of idioms with their （L2） English contextual representation these unknown idioms were used, and the third group was given （LI） Albanian translation equivalent. At the second stage, after learning and revising the unknown idioms for a period of four weeks, the participants received a common test consisting of two types of exercises-multiple-choice and fill-in-the-blanks-to check the impact of three techniques used for the long-term retention of idioms： definition, context, and translation. The results of the survey showed that the third-group students performed better than the two other groups who were exposed to English idioms definition and context; i.e., translation was the most effective technique that helped students＇ retention and acquisition of idioms.展开更多
There is a variety of PDSs （project delivery systems） in today＇s construction industry. This leads to confusion when it comes to selecting the most suitable PDS for a specific project. The wrong selection decision ...There is a variety of PDSs （project delivery systems） in today＇s construction industry. This leads to confusion when it comes to selecting the most suitable PDS for a specific project. The wrong selection decision might lead eventually to reduced profit margins or perhaps financial losses to PSFs （professional service firms）. This research proposes a conceptual framework that helps PSFs in the selection of one or more suitable PDSs for their construction operations. The framework uses SWOT （strengths, weaknesses, opportunities and threats） analysis as a tool for assessing each PDS considered in this research. The PDSs included in the framework are design-bid-build, design-build, construction management agency, public-private partnerships and integrated project delivery. The main aim of this research framework is to enhance decision-making efficiency in PDS selection for PSF operations.展开更多
基金The National Natural Science Foundation of China(No.60702028)the National High Technology Research and Development Program of China(863Program)(No.2007AA01Z268)
文摘Based on the frequency domain training sequences, the polynomial-based carrier frequency offset （CFO） estimation in multiple-input multiple-output （ MIMO ） orthogonal frequency division multiplexing （ OFDM ） systems is extensively investigated. By designing the training sequences to meet certain conditions and exploiting the Hermitian and real symmetric properties of the corresponding matrices, it is found that the roots of the polynomials corresponding to the cost functions are pairwise and that both meger CFO and fractional CFO can be estimated by the direct polynomial rooting approach. By analyzing the polynomials corresponding to the cost functions and their derivatives, it is shown that they have a common polynomial factor and the former can be expressed in a quadratic form of the common polynomial factor. Analytical results further reveal that the derivative polynomial rooting approach is equivalent to the direct one in estimation at the same signal-to-noise ratio（SNR） value and that the latter is superior to the former in complexity. Simulation results agree well with analytical results.
文摘A layered algorithm by bidirectional searching is proposed in this paper to solve the problem that it is difficult and time consuming to reach an optimal solution of the route search with multiple parameter restrictions for good quality of service. Firstly, a set of reachable paths to each intermediate node from the source node and the sink node based on adjacent matrix transformation are calculated respectively. Then a temporal optimal path is selected by adopting the proposed heuristic method according to a non-linear cost function. When the total number of the accumulated nodes by bidirectional searching reaches n-2, the paths from two directions to an intermediate node should be combined and several paths via different nodes from the source node to the sink node can be obtained, then an optimal path in the whole set of paths can be taken as the output route. Some simulation examples are included to show the effectiveness and efficiency of the proposed method. In addition, the proposed algorithm can be implemented with parallel computation and thus, the new algorithm has better performance in time complexity than other algorithms. Mathematical analysis indicates that the maximum complexity in time, based on parallel computation, is the same as the polynomial complexity of O(kn2-3kn+k), and some simulation results are shown to support this analysis.
文摘As far as we are concemed, one of the elements of assessing EFL/ESL （English as a Foreign Language/English as a Second Language） learners＇ language proficiency in institutions and universities in our country ＂lran＂ are multiple-choice reading comprehension tests. We also know that, it comprises one major section of the standard and TOEFL （Test of English as a Foreign Language） tests. Taking into account its importance and the problems which EFL learners have answered them, I get motivated to uncover some of the test-taking strategies which they employ to answer multiple-choice reading comprehension questions when dealing with familiar versus unfamiliar topics. To get a better conclusion, I choose 20 advanced male and female candidates whose English proficiency is at an acceptable level and at least at the same age level, and they major in English language from different colleges and universities. They are given two reading comprehension passages （familiar and unfamiliar）, each one with five final questions and allotted time to answer the questions. Two main instruments in this study are a retrospective think-aloud protocol and a semi-structured interview. The results of the reading comprehension tests and interview part revealed that advanced learners＇ high scores in the familiar topic were not because of their strategy use but because of their high linguistic and background knowledge on the topic. I also concluded that the number, kind, and sequence of strategies employed, were greatly dependent on the degree of testees＇ familiarity on the topic. In other words, test-takers used more strategies to compensate for their lack of linguistic knowledge.
文摘Six types of termites＇ baits （cartoon, rough tissues, soft toilet tissues, acacia wood, saw dust of building wood and sackcloth） were elicited variable degree of attraction toward Anacanthotermes ochaceus, where the best one was cardboard, followed by soft and rough toilet tissue at mono-choice and multiple-choice tests. Chemical analysis showed that there were variations in the chemical constituents （lignin, cellulose, N, H and C） of the six baits studied. On the other hand, olfactory reactions of harvester termites toward eight volatile oils （four natural medical plants and four commercial terpines） were repellent, but the most repellent one was cineol and the least one was clove oil. The most tested oils were caused inhibition in feeding, except cedar wood. The most toxic oils were cineol followed by thymol.
文摘This paper deals with the importance of idioms in English as a Foreign Language （EFL） acquisition in general and the effect of three techniques applied in teaching and learning them by the undergraduate university students in particular. To accomplish this aim, the study firstly tried to investigate English students＇ attitude toward learning L2 idioms through a 10-item questionnaire. The second part of the study passed on two stages; a list of 20 unknown idioms was presented to 30 second-year EFL students who were divided into three groups. The first group of students was given the list of idioms with （L2） English definition; the second group was given the same list of idioms with their （L2） English contextual representation these unknown idioms were used, and the third group was given （LI） Albanian translation equivalent. At the second stage, after learning and revising the unknown idioms for a period of four weeks, the participants received a common test consisting of two types of exercises-multiple-choice and fill-in-the-blanks-to check the impact of three techniques used for the long-term retention of idioms： definition, context, and translation. The results of the survey showed that the third-group students performed better than the two other groups who were exposed to English idioms definition and context; i.e., translation was the most effective technique that helped students＇ retention and acquisition of idioms.
文摘There is a variety of PDSs （project delivery systems） in today＇s construction industry. This leads to confusion when it comes to selecting the most suitable PDS for a specific project. The wrong selection decision might lead eventually to reduced profit margins or perhaps financial losses to PSFs （professional service firms）. This research proposes a conceptual framework that helps PSFs in the selection of one or more suitable PDSs for their construction operations. The framework uses SWOT （strengths, weaknesses, opportunities and threats） analysis as a tool for assessing each PDS considered in this research. The PDSs included in the framework are design-bid-build, design-build, construction management agency, public-private partnerships and integrated project delivery. The main aim of this research framework is to enhance decision-making efficiency in PDS selection for PSF operations.
