Mismatch Issue Research Articles

Design of a large aperture tunable refractive Fresnel liquid crystal lens.

A large aperture tunable lens based on liquid crystals, which is considered for near-to-eye applications, is designed, built, and characterized. Large liquid crystal lenses with high quality are limited by very slow switching speeds due to the large optical path difference (OPD) required. To reduce the switching time of the lens, the thickness is controlled through the application of several phase resets, similar to the design of a Fresnel lens. A main point of the paper is the design of the Fresnel structure to have a minimal effect on the image quality. Our modeling and experimental results demonstrate that minimal image degradation due to the phase resets is observable when the segment spacing is chosen by taking into account human eye resolution. Such lenses have applications related to presbyopia and, in virtual reality systems, to solve the well-known issue of accommodation-convergence mismatch.

Quary Expansion Using Local and Global Document Analysis

Automatic query expansion has long been suggested as a technique for dealing with the fundamental issue of word mismatch in information retrieval. A number of approaches to expansion have been studied and, more recently, attention has focused on techniques that analyze the corpus to discover word relationship (global techniques) and those that analyze documents retrieved by the initial query ( local feedback). In this paper, we compare the effectiveness of these approaches and show that, although global analysis haa some advantages, local analysia is generally more effective. We also show that using global analysis techniques.

Suspended individual SWCNT characterization via bottom gate FET configuration

AbstractThe microwave transmission properties of suspended, quasi‐metallic individual single‐walled carbon nanotubes (SWCNTs) with a bottom gate field‐effect transistor (FET) configuration have been investigated up to 10 GHz by standard two‐port S‐parameter measurements under different gate bias voltages. A tapered coplanar waveguide (CPW) transmission‐line test fixture is designed to overcome the parasitic and mismatch issues. An open‐through de‐embedding algorithm has been applied to extract the intrinsic properties of SWCNTs. And an equivalent circuit model has been proposed to fit the extracted measurement data as a function of the bottom gate bias voltage, facilitating the applications of CNTs into high‐frequency nanocircuits. Moreover, the properties of our transistor device are found to change after a period of time.

Monetary Policy Under Financial Dollarization: The Case of Eurasian Economic Union

Despite the general improvement in controlling price levels over the last two decades, a substantial number of the population in emerging market economies still save and borrow in foreign-denominated currencies. There are reasons to believe, however, that a high degree of financial dollarization presents obstacles in the transmission mechanisms of monetary policy and to the overall functioning of the financial sector. In the case of a typical developing economy – where external debts are denominated in foreign currency and domestic firms rely heavily on receipts in national currency – these difficulties are magnified. Financial dollarization in developing economies potentially leads to higher vulnerability of the domestic banking sector because of currency mismatch issues and large fluctuations in exchange rates, prompting the need for inflation-targeting monetary policy. This chapter investigates features of a high level of financial dollarization and the challenges it presents to inflation-targeting monetary policy in the Eurasian Economic Union. Based on a regression analysis, the chapter finds evidence that that the high level of financial dollarization in these countries tends to increase upward inflationary pressures at least in the short run, change the composition of total savings away from domestic currencies toward foreign ones, which potentially increases financial fragility in the banking sector. Thus, persistent high levels of financial dollarization imply that monetary policy is significantly limited through a greater exposure of banking sector to currency mismatches issues, which further increases demand for foreign assets.

Education Mismatch and Return Migration in Egypt and Tunisia

The objective of this paper is to shed light on the issue of education mismatch in the context of return migration in Egypt and Tunisia. Using data on both return and non-migrants in Egypt and Tunisia, we analyze the skills that migrants acquire before and during migration and the way these skills are used upon return. We find evidence of education mismatch, especially in Tunisia. Finally, we estimate the determinants of education mismatch on the Egyptian and Tunisian labour markets and find a significant positive effect of return migration on the probability of being overeducated.

An Efficient Corpus-Based Stemmer

Word stemming is a linguistic process in which the various inflected word forms are matched to their base form. It is among the basic text pre-processing approaches used in Natural Language Processing and Information Retrieval. Stemming is employed at the text pre-processing stage to solve the issue of vocabulary mismatch or to reduce the size of the word vocabulary, and consequently also the dimensionality of training data for statistical models. In this article, we present a fully unsupervised corpus-based text stemming method which clusters morphologically related words based on lexical knowledge. The proposed method performs cognitive-inspired computing to discover morphologically related words from the corpus without any human intervention or language-specific knowledge. The performance of the proposed method is evaluated in inflection removal (approximating lemmas) and Information Retrieval tasks. The retrieval experiments in four different languages using standard Text Retrieval Conference, Cross-Language Evaluation Forum, and Forum for Information Retrieval Evaluation collections show that the proposed stemming method performs significantly better than no stemming. In the case of highly inflectional languages, Marathi and Hungarian, the improvement in Mean Average Precision is nearly 50% as compared to unstemmed words. Moreover, the proposed unsupervised stemming method outperforms state-of-the-art strong language-independent and rule-based stemming methods in all the languages. Besides Information Retrieval, the proposed stemming method also performs significantly better in inflection removal experiments. The proposed unsupervised language-independent stemming method can be used as a multipurpose tool for various tasks such as the approximation of lemmas, improving retrieval performance or other Natural Language Processing applications.

Dataclay: A distributed data store for effective inter-player data sharing

In the Big Data era, both the academic community and industry agree that a crucial point to obtain the maximum benefits from the explosive data growth is integrating information from different sources, and also combining methodologies to analyze and process it . For this reason, sharing data so that third parties can build new applications or services based on it is nowadays a trend . Although most data sharing initiatives are based on public data, the ability to reuse data generated by private companies is starting to gain importance as some of them (such as Google, Twitter, BBC or New York Times) are providing access to part of their data. However, current solutions for sharing data with third parties are not fully convenient to either or both data owners and data consumers. Therefore we present dataClay, a distributed data store designed to share data with external players in a secure and flexible way based on the concepts of identity and encapsulation. We also prove that dataClay is comparable in terms of performance with trendy NoSQL technologies while providing extra functionality, and resolves impedance mismatch issues based on the Object Oriented paradigm for data representation.

Bridging Lanthanide to Quantum Dot Energy Transfer with a Short-Lifetime Organic Dye.

Semiconductor nanocrystals or quantum dots (QDs) should act as excellent Förster resonance energy transfer (FRET) acceptors due to their large absorption cross section, tunable emission, and high quantum yields. Engaging this type of FRET can be complicated due to direct excitation of the QD acceptor along with its longer excited-state lifetime. Many cases of QDs acting as energy transfer acceptors are within time-gated FRET from long-lifetime lanthanides, which allow the QDs to decay before observing FRET. Efficient QD sensitization requires the lanthanide to be in close proximity to the QD. To overcome the lifetime mismatch issues and limited transfer range, we utilized a Cy3 dye to bridge the energy transfer from an extremely long lived terbium emitter to the QD. We demonstrated that short-lifetime dyes can be used as energy transfer relays between extended lifetime components and in this way increased the distance of terbium-QD FRET to ∼14 nm.

Non-fragile state observation for delayed memristive neural networks: Continuous-time case and discrete-time case

The topic of non-fragile observation for memristive neural networks with both continuous-time and discrete-time cases are provided in this paper. By endowing the Lyapunov technique, the corresponding sufficient criteria for the stability findings are furnished in the form of linear matrix inequalities (LMIs), of which, the desired observer gains can be calculated via the LMIs. What is the difference lies that the driven memristive neural networks are recast into models with interval parameters when considering the fact that the parameters of memrisitve model are state-dependent, which lead to parameter mismatch issue when different initial values are given. Thus, a new robust control method is introduced to tackle with the target model. Finally, the analytical design are substantiated with numerical results.

A Study of Electrical Resistance in Carbon Nanotube–Insulator–Metal Diode Arrays for Optical Rectenna

Vertical tunnel diode arrays made from multiwall carbon nanotubes (MWCNTs) have shown recent promise for developing a practical optical rectenna, which is a device to convert electromagnetic waves at optical frequencies to direct current. Realizing an optical rectenna requires an antenna to be coupled to a diode that operates on the order of PHz (switching speed on the order of fs). Previously, we have demonstrated an optical rectenna device by engineering MWCNT–insulator–metal (MWCNT–I–M) tunnel diodes at the tips of vertically aligned MWCNT arrays, which act collectively as the antenna. However, the high electrical resistance of the MWCNT–I–M diode must be reduced to enable improved impedance matching between diode and antenna, which limited the rectified power in our prior work. Here, we address this issue of impedance mismatch through a series of experiments designed to elucidate contributions to the total electrical resistance of the device. Different combinations of metals, and metal and insulator thicknesses were tested for reduced contact resistance, while maintaining a working diode. Another development toward reducing resistance was to open MWCNT tips using oxygen plasma, which exposed multiple walls for bonding rather than just outer wall of closed tip CNTs. These developments were combined to reduce zero-bias resistance of MWCNT–I–M diode arrays to as low as 100 Ω ·cm2, which is 75 times lower than in our previous report.

Optimization of BSCF-SDC composite air electrode for intermediate temperature solid oxide electrolyzer cell

Solid oxide electrolyzer cells (SOECs) are devises which recently have attracted lots of attention due to their advantages. Their high operating temperature leads to mechanical compatibility issues such as thermal expansion mismatch between layers of material in the cell. The aim of this study is to mitigate the issue of thermal expansion mismatch between Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) and samaria doped ceria, Sm0.2Ce0.8O1.9 (SDC), enhance the triple-phase boundaries and improve the adhesion of the electrode to the electrolytes, hence improve the cell performance. To make BSCF more thermo-mechanically compatible with the SDC electrolyte, the formation of a composite electrode by introducing SDC as the compositing material is proposed. In this study, 10wt.%, 20wt.%, 30wt.%, 40wt.%, and 50wt.% of commercial SDC powder was mixed with BSCF powder, prepared by sol-gel method, to make the composite air electrode. After successfully synthesizing the BSCF-SDC/YSZ-SDC/Ni-YSZ electrolyzer cell, the electrochemical performance was tested for the intermediate-temperature SOEC (IT-SOEC), over the temperature range of 650–800°C. The microstructure of each sample was studied by field emission electron microscopy (FESEM, JEOL, JSM 6340F) for possible pin holes. The result of this study proves that the sample with 20% SDC-80% BSCF shows the highest performance among the investigated cells.

In brief

PAGE 2072 An in-situ procedure for measuring reflection coefficients by comparing the reflection from the ground surface and from a metallic plate has been proposed by researchers in Spain. Previous methods were limited by the nature and geometry of road surfaces and the weight of standard directive antennas. PAGE 2029 Researchers in Korea have devised a method for generating controlled, uniform near fields in antennas for RFID applications. Their method employs a cavity-backed anti-symmetric dual-loop fed by a coaxial cable with a quasi-balun, and the area of the loop's near field is controlled by sizing a slot printed on the back side of the radome cover. The measurement setup during the reference test. PAGE 2032 The potential of carbon nanotube FETs has been realised by researchers in Iran. They have developed an ultra-low power fuzzy SRAM for application in future multiple-valued CNT-based or hybrid MOS/CNT chips. Their design is also robust and reliable against misaligned CNTs and diameter variations. RFID antenna with and without the radome cover. PAGE 2040 Researchers in Korea have presented the highest radiofrequency power and the best power density among GaN power amplifiers with an octave bandwidth higher than the Ku-band. The drain lines and gate lines are shared among the combined non-uniform distributed amplifiers, and they produce a peak pulsed of about 40 W at 13 GHz. The conceptual model of the carbon nanotube device. PAGE 2034 Researchers in China have proposed a coarse-fine dual-loop digital low dropout regulator consisting of a binary weighed transistor array in the coarse loop and a 1-bit modulator in the fine loop. This technique means that the regulator not only reduces the number of power transistors significantly but also overcomes the mismatch and nonlinearity issues of the power transistor array. Record power in amplifiers can be achieved by sharing gate lines. The dropout regulator reduces power consumption and addresses non-linearity issues.

Analysis of Existence-Judging Criteria for Optimal Power Regions in DMPPT PV Systems

This paper quantitatively evaluates different distributed maximum power point tracking (DMPPT) photovoltaic (PV) systems in mismatch cases. To help designers obtain the full benefits of the DMPPT concept, a general analysis of the optimal power region (OPR) in different DMPPT system configurations is undertaken. Taken into account in the evaluation of OPRs are functional constraints derived from DMPPT converters, mismatch conditions, and system architectures and parameters of related PV units. To simplify the calculation process and enable rapid discovery of OPRs, judging criteria are proposed for 4 DMPPT structures. If the judging criteria are met, DMPPT PV systems can extract ideal maximum power regardless of mismatch issues. Finally, experimental results are provided to show the effectiveness of the proposed static models, formulas, and judging criteria.

Bridging new and old energy

Bridging new and old energy

A Study on the Taxation Issue of the Hybrid Mismatch - Focused on the Hybrid Entity and Hybrid Instrument -

A Study on the Taxation Issue of the Hybrid Mismatch - Focused on the Hybrid Entity and Hybrid Instrument -

Housing Mismatch Model in Suburban Areas

Abstract Housing mismatch becomes vital issues to studies; it happens due to inequality of housing demand and supply in the property market. Housing mismatch has generated by various factors and situation based on the demographic profile in neighborhood areas. However, the most area appears to have different aspect and issues of housing mismatch. This paper aims to review the situation exist in housing mismatch and to identify the elements in measuring the inequality based on literature. Also, the result will be compiled through a creation of framework model. The study is still in progress and will identify the exact contribution of housing dispersion and phenomenon through selected areas. Identification of these contributes to local communities, private institution, and the government in facilitating them towards the better-living conditions.

Dynamic Uplink - Downlink Configuration in TD-LTE with HARQ Feedback

Mobile communication has become data centric and data traffic is increasing exponentially. LTE systems were originally designed for symmetric & almost fixed uplink and downlink capacity distribution. The pattern of data usage is dynamic and incommensurable for uplink and downlink. Enhanced Interference Mitigation and Traffic Adaptation (eIMTA) is one of the features which enable TD-LTE systems to handle asymmetric and dynamic uplink and downlink capacity requirements. eIMTA allows dynamic changes to configurable TDD patterns for uplink and downlink. There are impacts on HARQ timeline, acknowledgement transmission timing because of changes in uplink & downlink configuration. This paper explains eIMTA and HARQ timeline issues and proposes semi-static HARQ timeline mechanism. SIB1 indicated uplink HARQ reference configuration for each serving cell solves uplink sub-frame mismatch issue. Device can derive reference configuration for each cell's uplink and downlink HARQ on basis of HARQ timeline. Downlink HARQ based soft buffer partitioning has semi-static changes, which helps to minimize throughput loss.

Unstructured Cartesian refinement with sharp interface immersed boundary method for 3D unsteady incompressible flows

A novel numerical method is developed for solving the 3D, unsteady, incompressible Navier–Stokes equations on locally refined fully unstructured Cartesian grids in domains with arbitrarily complex immersed boundaries. Owing to the utilization of the fractional step method on an unstructured Cartesian hybrid staggered/non-staggered grid layout, flux mismatch and pressure discontinuity issues are avoided and the divergence free constraint is inherently satisfied to machine zero. Auxiliary/hanging nodes are used to facilitate the discretization of the governing equations. The second-order accuracy of the solver is ensured by using multi-dimension Lagrange interpolation operators and appropriate differencing schemes at the interface of regions with different levels of refinement. The sharp interface immersed boundary method is augmented with local near-boundary refinement to handle arbitrarily complex boundaries. The discrete momentum equation is solved with the matrix free Newton–Krylov method and the Krylov-subspace method is employed to solve the Poisson equation. The second-order accuracy of the proposed method on unstructured Cartesian grids is demonstrated by solving the Poisson equation with a known analytical solution. A number of three-dimensional laminar flow simulations of increasing complexity illustrate the ability of the method to handle flows across a range of Reynolds numbers and flow regimes. Laminar steady and unsteady flows past a sphere and the oblique vortex shedding from a circular cylinder mounted between two end walls demonstrate the accuracy, the efficiency and the smooth transition of scales and coherent structures across refinement levels. Large-eddy simulation (LES) past a miniature wind turbine rotor, parameterized using the actuator line approach, indicates the ability of the fully unstructured solver to simulate complex turbulent flows. Finally, a geometry resolving LES of turbulent flow past a complete hydrokinetic turbine illustrates the potential of the method to simulate turbulent flows past geometrically complex bodies on locally refined meshes. In all the cases, the results are found to be in very good agreement with published data and savings in computational resources are achieved.

Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags.

A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919–923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for ‘place and tag’ application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP).

Optoelectronic devices based on two-dimensional transition metal dichalcogenides

In the past few years, two-dimensional (2D) transition metal dichalcogenide (TMDC) materials have attracted increasing attention of the research community, owing to their unique electronic and optical properties, ranging from the valley–spin coupling to the indirect-to-direct bandgap transition when scaling the materials from multi-layer to monolayer. These properties are appealing for the development of novel electronic and optoelectronic devices with important applications in the broad fields of communication, computation, and healthcare. One of the key features of the TMDC family is the indirect-to-direct bandgap transition that occurs when the material thickness decreases from multilayer to monolayer, which is favorable for many photonic applications. TMDCs have also demonstrated unprecedented flexibility and versatility for constructing a wide range of heterostructures with atomic-level control over their layer thickness that is also free of lattice mismatch issues. As a result, layered TMDCs in combination with other 2D materials have the potential for realizing novel high-performance optoelectronic devices over a broad operating spectral range. In this article, we review the recent progress in the synthesis of 2D TMDCs and optoelectronic devices research. We also discuss the challenges facing the scalable applications of the family of 2D materials and provide our perspective on the opportunities offered by these materials for future generations of nanophotonics technology.