This paper proposes an idea to modify the conventional Wilkinson power dividers to have physically spaced output ports. The well-known internal resistor of Wilkinson power divider is now connected to output ports by two additional transmission lines to create a triangular shape power divider. Several modified power dividers are designed at frequency of 1.0 GHz and one of them is fabricated and measured. The measured results of the fabricated diplexer have very good agreement with the theoretical results.

ABSTRACTDuring the last century, ports of Persian Gulf become the most important storage, refining and transportation of crude oil, oil derivation, petrochemical products and also, business activities. Nowadays, due to functional diversity between ports, the impact of port activities on the development of urban spaces will be different, and this issue leads to structural differences of port cities. The purpose of this research is to identify the key variables affecting the relations and spatial structure of port-city in Dubai as the most thriving and successful port-city in the Persian Gulf. This research is based on deductive reasoning and carried out by analysis of cross effects with secondary data (results of other prominent articles) and also primary data (questionnaire). sampling method is based on purposive sampling and Micmac software was used to analyze the data. Output of Micmac software shows the position of the instability of the system. Therefore, the position of each variables in the conceptual model can be categorized to driver, linkage, dependent, and autonomous factors. The research findings indicate 4 variables (like as “income, cost and investmnets in port-city”) can be introduced as a driver factor, 5 variables (like as “advanced multimodal transportation in the port”) can be introduced as a linkage factor, 6 variables (like as “quality of living environment and desirable city”) can be introduced as a dependent factor, 3 variables (like as “environmental protection and sustainable development of the city-port”) can be introduced as an autonomous factor. The rapid development of Dubai can be explained by the purposeful distribution of revenues from trade and tourismExtended AbstractIntroductionDuring the last century, ports of Persian Gulf become the most important storage, refining and transportation of crude oil, oil derivation, petrochemical products and also, business activities. The global increase in oil demand since the 1950s led to the creation of discovery of new oil wells and large industrial areas. With the construction of new oil or gas facilities in the port areas, increasing oil revenues contributed to the countries of the Persian Gulf region and form a new geographical relationship between ports and coastal cities which had an impact on the spatial structure and relation of them. Nowadays, due to functional diversity between ports, the impact of port activities on the development of urban spaces will be different, and this issue leads to structural differences of port cities. In the 1950s, Containerization (container loading technology) was based in some of the world's ports and created a huge transformation in the shipping industry, which had a significant impact on the development of ports. Although the ports of the Persian Gulf have made a significant contribution to the economic growth and physical development of other ports in the world, but few researches have been done on the variables and factors affecting the development of the spatial structure of the important ports of the Persian Gulf. This region, due to its unique geographical location, has always been considered as a most important corridor in the field of economic and transportation throughout history. Some of the most important energy and commercial ports in this region are: Dubai, Manama, Kuwait, Dammam, Doha, Bushehr, Bandar-Abbas and Assaluyeh. In this regard, the purpose of this research is to identify the key variables affecting the relations and spatial structure of port-city in Dubai as the most thriving and successful port-city in the Persian Gulf. MethodologyThis research is based on deductive reasoning and carried out by analysis of cross effects with secondary data (results of other prominent articles) and also primary data (questionnaire). The method used in this research is quantitative and the sampling method is based on purposive sampling. the variables affecting the spatial structure of port-city relations were identified in the form of a review of 31 prominent articles. 25 experts (who had comprehensive knowledge and information about the development process of the city-port of Dubai) participated to determine the effectiveness or influence of variables. Finally, the output of data analysis was done by the Micmac software. Results and discussionOutput of Micmac software shows the position of the variables in the diagram that it indicates their status in the system and their role in the dynamics and changes of the system. The method of distribution and dispersion of the variables in the spatial structure of port-city relations indicates the instability of the system. Therefore, based on the output of the system, the position of each variables in the conceptual model can be identified in five categories (driver, linkage, dependent, autonomous and regulatory variables). According to the results, some variables such as “the changes in the strategic positions” and “geopolitics of port-city”, “the modification of the management method” and “regional planning of the ports”, “the promotion of local governance in the relations between port-city” and “the way of national and international management of ports have been introduced as driver variables. On the other hand, five variables consist of “advanced multimodal transportation in the port” and “income, cost and investment in the port-city”, “the contrast and physical integration of the port - city space”, “the development of various industrial and production activities in the ports and their local hinterland” and “their qualities Financial and commercial policies of ports” have been introduced as linkage variables. Findings of research also shows that some variables consist of “quality of living environment and desirable city”, “quantity and quality of transit corridors (rail, road and air) to hinterland”, “construction and launching the new port (sea port or dry port)”, “terminal facilities and infrastructure and warehousing”, “conflict or convergence between the city and the port” and “increase in population growth rate and migration to the port - city” categorized as dependent variables. Three variables including “cultural and historical background of ports”, “use of cheaper energy, Less-polluted, clean and renewable energies in the city-port” and “environmental protection and sustainable development of the city-port” categorized as autonomous variables. Finally, a variable with the title of “improvement in management and information technology and development in loading, unloading and storage of commodities” have been introduced as regulatory variables. The findings of this research have a remarkable similarity with other researches carried out in the field of city-port relation and clearly emphasize the direct impact of the "investment in port-city" in the development of them. For example, Grossmann (2008) emphasized that city-port of Hamburg has become one of the largest ports in Northern Europe during the last few decades due to huge domestic and foreign investment. ConclusionThis research carried out in order to introduce and explain the key variables affecting the development of the spatial structure of the port-city of Dubai. On this basis, 21 variables have been extracted by systematic reviews of prominent articles. In the following, 25 experts were selected with the purposive sampling method. Among the 21 variables extracted, 4 variables (like as “geopolitics of port-city”) introduced as a driver factor, 5 variables (like as “advanced multimodal transportation in the port”) introduced as a linkage factor, 6 variables (like as “quality of living environment and desirable city”) introduced as a dependent factor, 3 variables (like as “environmental protection and sustainable development of the city-port”) introduced as an autonomous factor. The rapid development of Dubai can be explained by the purposeful distribution of revenues from trade and tourism. A part of these revenues has been directed towards investment in important transportation infrastructures such as airports and ports of this city. These strategies have a wide impact on improving the economic growth of the city and the development of the port in order to adapt with the global trade and advanced technologies. FundingThere is no funding support. Authors’ ContributionAuthors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work declaration of competing interest none. Conflict of InterestAuthors declared no conflict of interest. Acknowledgments We are grateful to all the scientific consultants of this paper.

Formulaic sequences (FSs) are among the most commonly discussed and well-documented effective factors in oral fluency both in L1 and L2. The present study aims to investigate the effect of teaching a set of 140 FSs on Iranian EFL learners' oral fluency. The relationship between the use of FSs and different measures of oral fluency is also studied empirically. Forty-eight intermediate EFL learners took part in the study. The participants were randomly assigned into two experimental groups and one control group. One of the experimental groups was taught the FSs with spaced retrievals. The other experimental group was also taught the FSs but with non-spaced retrievals. The control group was taught no FSs. The posttest was conducted one week after the treatment. Multivariate analysis of variance (MANOVA) and other statistical procedures were used for analyzing the data. The results indicated that spaced productive retrieval of the FSs after their explicit and holistic teaching, helped the learners to have longer mean length of runs. The present findings have important implications for solving students' problems in speaking the second language. Therefore, the significance of spaced retrieval of FSs in language teaching and learning should not be neglected.

Background: Even though there are diverse varieties of teaching methods to motivate and educate students, not many are used in dental institutions, where most rely only on traditional lectures. Hence, the objective of this study was to compare traditional lectures with newer teaching methods, specifically the flipped classroom and spaced learning method. Materials and Methods: In this prospective cohort study Students were randomized to one of the teaching methods, and their short‑ term (immediately after teaching) and long‑ term (i. e., 6 months later) knowledge retention was assessed through multiple choice questions, followed by students feedback which was obtained using Trierer Inventar zur Lehrevaluation questionnaire. P ≤ 0. 05 was considered statistically significant. Results: For short‑ term learning gains, spaced learning group (165. 85) showed highest mean scores, followed by the traditional lecture group (163. 70) and flipped classroom group (153. 25). P value acquired through the Kruskal– Wallis ANOVA was statistically significant (0. 003). For long‑ term knowledge retention, traditional lecture group has highest mean scores (147. 50), followed by spaced learning group (146. 90) and flipped classroom group (145. 05) with no significant difference (P = 0. 657). Conclusion: Spaced learning methodology was better than the traditional lecture method and the flipped classroom concerning knowledge gains when measured immediately after the application of learning method. For long‑ term knowledge retention, both the flipped classroom and spaced learning teaching methods were comparable to the traditional lecture method.

The closely spaced modes exist in symmetric structures such as circular plates, gears or disks. Theoretically, closely spaced modes are known as two separated modes with the same amount, but these modes are often detected as only one mode in the classical modal methods. In this article, at the first, some classical modal method is introduced and the most important of their difficulties is considered. Then, Operational Modal Analysis (OMA) is applied to abate these problems. The Stochastic Subspace Identification based on covariance (SST-COV) driven is used for this purpose. Different conditions for closely spaced modes is considered and simulated on a free-free steel plate using Matlab software. Tn order to consider the SSI-COV method in identification of closely spaced modes experimentally, classical and operational modal testing are done on a steel ring. The numerical and experimental results from simulations demonstrate the effectiveness of OMA for identifying and separating the close modes.

High gain Balun-low-noise-amplifier (LNA) is proposed for tuner of digital televisions (DTVs). The proposed Balun-LNA is based on CS-CG (common-source-common-gate) structure. To improve the isolasion and frequency response, Balun-LNA has cascode transistors before load resistors. Balun-LNA uses current-bleeding circuit to increasie transconductance of CS transistor, so that current-bleeding transistor has transconductance of N-1 times larger than transconductance of cascode transistor. Thereby, transconductance and current of CS transistor are increased N times, as N-1 times of current pass to current-bleeding transistor. Therefore current of CG and CS stages stay identical. Also, Balun-LNA employs a positive feedback to satisfy input impedance matching and CG transistor has higher transconductance. By increasing transconductance of CS and CG transistors, the proposed Balun-LNA achieves to high voltage gain. Accordingly, CG and CS tansistors have symmetrical currents and loads at the differential output of the proposed Balun-LNA. Symmetrical loads cause the balanced differential outputs. This proposed Balun-LNA is designed in 90-nm CMOS technology and covers the frequency range of 40 MHz to 1GHz. This Balun-LNA achieves the voltage gain of 22.6 dB, S11 of less than -10 dB and the Minimum NF of 5 dB. This Balun-LNA operates at the nominal supply voltage of 2.2v.

The position of the planets for the planetary gear systems are in two forms of equally and unequally spaced. This paper investigates free vibration of the planetary gear with unequally spaced planets. The planetary gear set of this study is modeled as a set of lumped masses and springs. Each component such as sun gear, carrier, ring gear and planets possesses three degrees of freedom and is considered as rigid body. Bearing and mesh stiffness are modeled in the form of linear springs. Generally, planet, rotational, translational, distinct and degenerate modes are five vibration modes of the planetary gear systems. The results show that the translational mode for the system with numbers of even equally and unequally spaced planets, is different and rotational and translational modes have the same characteristics for both systems. For the system with numbers of even unequally spaced planets, the natural frequencies of the translational modes have a multiplicity one. When the numbers of the planets of the system are odd and the position of them is unequally spaced, the rotational and planet modes are generated and the natural frequencies of the translational modes do not appear. For the distinct and degenerate modes of the system with unequally spaced planets, the planets only have the rotational motion.

The choice of a suitable bearing capacity of soil becomes the most important issue to be considered in any project. This paper describes analytical investigation conducted to evaluate the ultimate bearing capacity of adjacent footings in various spacings of footings. Bearing capacity of adjacent footings is determined based on virtual retaining wall method by applying equilibrium between active and passive forces. Results indicate the ultimate bearing capacity of each foundation changes due to the interference effect of the failure surface in the soil and it depends on footings spacing. In the present study, effect of soil type, depth of adjacent footings and reinforced soil is investigated on bearing capacity of adjacent footings. Results indicate closely spaced footings, can decrease or increase bearing capacity of adjacent footings with respect to single footings. Also, reinforced soil increases bearing capacity of closely spaced footings with respect to single footings on unreinforced soil, it depends on footings spacing. Finally, the predicted results are compared with those reported from experiments, analytical and numerical results performed by others, indicating an acceptable agreement.