bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimación de funciones de producción en microempresas informales de la ciudad de Osorno, Chile
Authors: Antipa Castillo Camila , Morales Soto Rodrigo , Ferrada Bórquez Luz María
Published: August 2013

En este trabajo se estiman funciones de producción para microempresas informales del sector urbano de la comuna de Osorno, Chile. La metodología consiste en construir una matriz insumo producto con base en los antecedentes de la estructura de compras de empresas informales de la ciudad, dicha matriz se adecua para lograr los propósitos de la investigación, donde se analiza la estructura productiva y los componentes del valor agregado de los sectores comercio, servicios y manufactura. A pesar de que son sectores muy distintos, se verifica que no existen importantes diferencias en la composición del valor agregado y que los impuestos que pierden por la condición de informalidad, no son relevantes en el excedente
Instabilities of the flow around a cylinder and emission of vortex dipoles
Authors: Kizner Ziv , Makarov Viacheslav , Kamp Leon , van Heijst GertJan
Published: August 2013

Instabilities and long-term evolution of two-dimensional circular flows around a rigid circular cylinder (island) are studied analytically and numerically. For that we consider a base flow consisting of two concentric neighbouring rings of uniform but different vorticity, with the inner ring touching the cylinder. We first study the inviscid linear stability of such flows to perturbations of the free edges of the rings. For a given ratio of the vorticity in the rings, the governing parameters of the problem are the radii of the inner and outer rings scaled on the cylinder radius. In this two-dimensional parameter space, we determine analytically the regions of linear stability/instability of each azimuthal mode $m= 1, 2, \ldots . $ In the physically most meaningful case of zero net circulation, for each mode $m\gt 1$, two regions are identified: a regular instability region where mode $m$ is unstable along with some other modes, and a unique instability region where only mode $m$ is unstable. After the conditions of linear instability are established, inviscid contour-dynamics and high-Reynolds-number finite-element simulations are conducted. In the regular instability regions, simulations of both kinds typically result in the formation of vortical dipoles or multipoles. In the unique instability regions, where the inner vorticity ring is much thinner than the outer ring, the inviscid contour-dynamics simulations do not reveal dipole emission. In the viscous simulation, because viscosity has time to widen the inner ring, the instability develops in the same manner as in the regular instability regions.
William Harvey, Aristotle and astrology
Authors: GREGORY ANDREW
Published: August 2013

In this paper I argue that William Harvey believed in a form of astrology. It has long been known that Harvey employed a macrocosm–microcosm analogy and used alchemical terminology in describing how the two types of blood change into one another. This paper then seeks to examine a further aspect of Harvey in relation to the magical tradition. There is an important corollary to this line of thought, however. This is that while Harvey does have a belief in astrology, it is strongly related to Aristotle's views in this area and is quite restricted and attenuated relative to some contemporary beliefs in astrology. This suggests a more general thesis. While Harvey was amenable to ideas which we associate with the natural magic tradition, those ideas had a very broad range of formulation and there was a limit to how far he would accept them. This limit was largely determined by Harvey's adherence to Aristotle's natural philosophy and his Christian beliefs. I argue that this is also the case in relation to Harvey's use of the macrocosm–microcosm analogy and of alchemical terminology, and, as far as we can rely on the evidence, this informs his attitudes towards witches as well. Understanding Harvey's influences and motives here is important in placing him properly in the context of early seventeenth-century thought.
Monitoring immune modulation by nutrition in the general population: identifying and substantiating effects on human health
Authors: Albers Ruud , Bourdet-Sicard Raphaëlle , Braun Deborah , Calder Philip C. , Herz Udo , Lambert Claude , Lenoir-Wijnkoop Irene , Méheust Agnès , Ouwehand Arthur , Phothirath Phoukham , Sako Tomoyuki , Salminen Seppo , Siemensma André , van Loveren Henk , Sack Ulrich
Published: August 2013

Optimal functioning of the immune system is crucial to human health, and nutrition is one of the major exogenous factors modulating different aspects of immune function. Currently, no single marker is available to predict the effect of a dietary intervention on different aspects of immune function. To provide further guidance on the assessment and interpretation of the modulation of immune functions due to nutrition in the general population, International Life Sciences Institute Europe commissioned a group of experts from academia, government and the food industry to prepare a guidance document. A draft of this paper was refined at a workshop involving additional experts. First, the expert group defined criteria to evaluate the usefulness of immune function markers. Over seventy-five markers were scored within the context of three distinct immune system functions: defence against pathogens; avoidance or mitigation of allergy; control of low-grade (metabolic) inflammation. The most useful markers were subsequently classified depending on whether they by themselves signify clinical relevance and/or involvement of immune function. Next, five theoretical scenarios were drafted describing potential changes in the values of markers compared with a relevant reference range. Finally, all elements were combined, providing a framework to aid the design and interpretation of studies assessing the effects of nutrition on immune function. This stepwise approach offers a clear rationale for selecting markers for future trials and provides a framework for the interpretation of outcomes. A similar stepwise approach may also be useful to rationalise the selection and interpretation of markers for other physiological processes critical to the maintenance of health and well-being.
Creeping Forest and (Dis)Placed Bodies: Relocating Racial Trauma in Angelina Weld Grimké's “Blackness” and “Goldie”
Authors: PHILLIPS LINDSEY
Published: August 2013

In this essay, I rethinkplacein terms of the traumatic experience of lynching through Angelina Weld Grimké's “Blackness” and “Goldie,” which fictionalize Mary Turner's 1918 lynching in Georgia. Grimké's stories, I argue, place racial tensions within an American landscape and challenge the potential erasure that often occurs by viewing landscape only through white experience. “Blackness” and “Goldie,” as examples of black nature writing, exhume the memory of lynching and reveal the constructiveness of nature. By analyzing the racialized construction of a southern landscape, I contend that racial terror impacts the meaning of nature and argue that place can be reconstituted in the mind through memories associated with it. Even though Grimké relocates “Blackness” in the North, the protagonist cannot escape traumatic memories of lynching. Instead, his memories of racial violence stay in “place” and begin to affect Reed, his law partner from the North, as well as the reader. Thus this essay reveals how racial trauma transforms the meaning of nature and reinvents place, and through the protagonists' traumatic memories of the trees and hanging black bodies, the southern landscape “creaks,” voicing black oppression that threatens to engulf both white and black.
Gender and the Dies Committee Hearings on the Federal Theatre Project
Authors: DOSSETT KATE
Published: August 2013

This paper examines the House Committee on Un-American Activities and Propaganda's investigation into un-American activities in the Federal Theatre Project. In particular it examines the performances of committee chairman Martin Dies and his Republican colleague J. Parnell Thomas, who led the interrogation of Federal Theatre witnesses. Relying on so-called “friendly witnesses,” usually disaffected former Federal Theatre employees or former communists, Dies and Thomas devoted three days to the testimony of Hazel Huffman, a WPA mail clerk, who never worked on the FTP, while allowing Hallie Flanagan and Ellen Woodward, the two women who directed the national theatre programme, just a few hours each. While Huffman gushed and flirted, Flanagan and Woodward refused to perform the version of femininity the committee demanded. The reordering of gendered roles that resulted was startling. The Dies Committee took to presenting itself as emasculated, a victim of masculine women and New Deal–communist conspirators, who were stripping not only them, but also America, of manhood. This paper suggests that it is only by analysing the powerful gendered performances of the key characters in this unfolding drama of un-Americana that we can understand how and why un-Americanism gained so strong a foothold in mid-century America.
A Moveable Feast: The UFW Grape Boycott and Farm Worker Justice
Authors: Garcia Matt
Published: August 2013

When most people think of the United Farm Workers, two things come to mind: Cesar Chávez and the grape boycott. Regarding the former, Chávez distinguished himself as perhaps the best-known Mexican American labor and civil rights leader in the country through his advocacy for farm worker rights in California during the 1960s and 1970s. In 1970, the union he led forced growers to the bargaining table for the first farm labor contracts in the history of the Golden State. This achievement would not have been possible without Chávez's embrace of the boycott, a strategy that, until proven important to the struggle, had been regarded by labor leaders as supplemental to the main strategies of strikes and marches. In fact, when we evaluate the contributions of the United Farm Workers to the history of labor in the United States, the grape boycott might well be its most enduring legacy, even more so than Chávez's leadership.
A Self-Inflicted Wound: Cesar Chávez and the Paradox of the United Farm Workers
Authors: Pawel Miriam
Published: August 2013

In the late 1970s, the future of organized labor in the fields of California had never looked brighter. A decade of boycotts, strikes, and marches had generated public and political pressure that culminated in the California Agricultural Labor Relations Act—“the best labor law in the country,” the United Farm Workers’ chief negotiator triumphantly proclaimed in June 1975. Soon thereafter, the Teamsters agreed to withdraw and cede organizing in the fields to Cesar Chávez's union, ending a costly and violent rivalry.
Introduction to a 1995 Conversation with Eric Hobsbawm
Authors: Hanagan Michael , Moazami Behrooz
Published: August 2013

Eric Hobsbawm, who died on October 1, 2012, was one of a handful of extraordinary labor historians who emerged from the British Communist Party Historians' Group in the 1940s and 1950s. Today he is widely acknowledged as one of the great historians of our era. His influence is truly international. For a long time, a significant limitation on the extent of his renown was the USSR where, during the era of “actually-existing socialism,” his works were never translated or published. This was ironic since he was a card-carrying member of the Communist Party of Great Britain (CPGB) from 1936 until its dissolution in 1991.
Contesting Class Organization: Migrant Workers’ Strikes in China's Pearl River Delta, 1978–2010
Authors: Chan Chris King-Chi
Published: August 2013

This article analyzes the process of working-class formation under the ongoing industrialization in China by studying how the trade union has been contested by migrant workers in their strikes in the Pearl River Delta (PRD) over the past three decades. The cases presented here are emblematic of workers’ struggles that have aroused public attention in the specific period of analysis. The author suggests that the trade union as a class organization has been a contested domain for migrant workers’ struggles in the PRD. Through their collective actions, workers’ class consciousness and strategies towards class organization have steadily advanced in the process of China's integration into the global economy.
The Ties Allowed to Bind: Kinship Legalities and Migration Restriction in the Interwar Americas
Authors: Putnam Lara
Published: August 2013

New immigration restrictions in the United States and elsewhere in the 1920s and 1930s made legal entry dependent on specific kinship formalities. This article explores the impact of the new system through a study of British Caribbean migrants. Because family patterns and the place of church and state sanction within them varied greatly by class—here, as in many parts of the world—the result was a curtailment of mobility that affected elites very little, and working-class would-be migrants enormously. In order to elucidatede factopatterns of exclusion, the author concludes, historians of transnational labor must begin paying more attention to the work “family” does.
Notes from Marikana, South Africa: The Platinum Miners’ Strike, the Massacre, and the Struggle for Equivalence
Authors: Magaziner Daniel , Jacobs Sean
Published: August 2013

This note reflects on the August 2012 miners' strike at Marikana, South Africa in light of a century long history of violence associated with worker actions in that country and elsewhere in the Global South. It suggests that the breakaway union's allegedly ‘illegal’ strike fits within a long tradition of radical worker activism in South Africa, which is best understood in light of anticolonial efforts to short-circuit the chronologies of imperial power. The Marikana strike, like anticolonial rebellions during the early twentieth century and, critically, white worker struggles following First World War, was an effort to speed up the process by which the value of workers’ lives and labor might be made equivalent to those in power.
Strikes and Pickets in Brazil: Working-Class Mobilization in the “Old” and “New” Unionism, the Strikes of 1957 and 1980
Authors: Fontes Paulo , de Macedo Francisco Barbosa
Published: August 2013

This article analyzes the role of pickets in two of the most emblematic strikes in Brazilian labor history during the twentieth century: the “strike of the 400,000,” which involved several industry categories in São Paulo and neighboring cities in 1957, and the “forty-one days strike” in 1980 involving the metalworkers of the industrial belt, known as ABC Paulista, in the metropolitan region of the city of São Paulo. Both strikes broke out at a time of profound reconfiguration of Brazilian society, marked by industrialization, migration, and urbanization processes. Although separated by a time gap of almost twenty-five years, both the “strike of the 400,000” and the “forty-one days strike” reveal important aspects of the performance of workers in that crucial period of Brazilian history.
Comparison of standalone performance between COMPASS and GPS
Authors: Ji Shengyue , Xu Ying , Chen Wu , Wang Zhenjie , Weng Duojie , Huang Binghu , Fan Shijie , Sun Genyun
Published: August 2013

COMPASS or BeiDou is the new satellite navigation system under construction in China. In this paper, the standalone performance of COMPASS is compared to the Global Positioning System (GPS), including: Single Point Positioning (SPP), differential positioning (DGPS and Differential COMPASS) and single epoch ambiguity resolution and positioning. Based on the results, it was found that COMPASS SPP performance is clearly worse than that of GPS, due to larger broadcast orbit and satellite clock errors, especially the latter. Differential positioning performance of COMPASS and GPS are essentially similar, with GPS marginally better. COMPASS single epoch ambiguity resolution performance is obviously better than that of GPS due to more observed satellites and the single epoch positioning performance of COMPASS and GPS are similar.
TRAZOM'S WIT: COMMUNICATIVE STRATEGIES IN A ‘POPULAR’ YET ‘DIFFICULT’ SONATA
Authors: BYROS VASILI
Published: August 2013

Vienna, 21 August 1773: Mozart signs off a letter to his sister Nannerl in his usual jocular manner: ‘oidda – gnagflow Trazom neiw ned 12 tsugua 3771’. This ‘arseways’ spelling of his signature is an early example of Mozart's well-known fondness for jesting and playing with patterns – spatial, arithmetical, linguistic and musical. Mozart appears to have been especially committed to such games in the 1770s. This was a period when he was also involved with the more serious matter of advancing his career, in which the composition of the first six so-called ‘difficult’ yet also ‘popular’ keyboard sonatas,k279–284, played an integral part. This article reads certain inexplicable gestures in the first sonata,k279,as reflecting Mozart's preoccupation with witty expressions at this time, seemingly as part of his attempt to gain the favour of prospective patrons, publishers and employers. The idiosyncrasies of the sonata result from an intersection of the syntax of phrase-level patterning and large-scale form with the semiosis of musical topics, eliciting laughter or simply a smile. Mozart's communicative strategy is situated in a broader context of the compositional play, wit and humour discussed in late eighteenth-century theory and aesthetics. It also allows us to revisit several implications arising from Danuta Mirka and Kofi Agawu'sCommunication in Eighteenth-Century Musicof 2008, including the importance of ‘context’ for successful communication, the susceptibility of eighteenth-century artefacts to present-day misreading and the problem ofKenner, Liebhaberand audiences in general.
Rhythmic Accent and the Absolute: Sulzer, Schelling and theAkzenttheorie
Authors: MCAULEY TOMAS
Published: August 2013

1770s Berlin saw the birth of a new theory of rhythm, first stated in Johann Georg Sulzer'sAllgemeine Theorie der schönen Künste(1771–1774), and later labelled theAkzenttheorie(theory of accents). Whereas previous eighteenth-century theories had seen rhythm as built up from the combination of distinct units, theAkzenttheoriesaw it as formed from the breaking down of a continual flow, achieved through the placing of accents on particular notes. In hisPhilosophie der Kunst(1802–1803) the philosopher Friedrich Schelling used Sulzer's definition of rhythm to suggest, astonishingly, that music can facilitate knowledge of the absolute, a philosophical concept denoting the ultimate ground of all reality. In this article I show how Schelling could come to interpret theAkzenttheoriein such extravagant terms by examining three theories of time and their relationships to rhythm: that of Sulzer and his predecessor Isaac Newton, that of Immanuel Kant and that of Schelling. I conclude by arguing that in Schelling's case – an important one, since his is the earliest systematic presentation of a view of music that came to predominate in the decades after 1800 – his view of music was driven neither by developments in contemporary music nor by changes in the philosophy of art as a discrete intellectual enterprise, but by revolutions in philosophy by and large unconcerned even with art in general.
Mechanisms of RNA-induced toxicity in CAG repeat disorders
Authors: Nalavade R , Griesche N , Ryan D P , Hildebrand S , Krauß S
Published: August 2013

Several inherited neurodegenerative disorders are caused by CAG trinucleotide repeat expansions, which can be located either in the coding region or in the untranslated region (UTR) of the respective genes. Polyglutamine diseases (polyQ diseases) are caused by an expansion of a stretch of CAG repeats within the coding region, translating into a polyQ tract. The polyQ tract expansions result in conformational changes, eventually leading to aggregate formation. It is widely believed that the aggregation of polyQ proteins is linked with disease development. In addition, in the last couple of years, it has been shown that RNA-mediated mechanisms also have a profound role in neurotoxicity in both polyQ diseases and diseases caused by elongated CAG repeat motifs in their UTRs. Here, we review the different molecular mechanisms assigned to mRNAs with expanded CAG repeats. One aspect is the mRNA folding of CAG repeats. Furthermore, pathogenic mechanisms assigned to CAG repeat mRNAs are discussed. First, we discuss mechanisms that involve the sequestration of the diverse proteins to the expanded CAG repeat mRNA molecules. As a result of this, several cellular mechanisms are aberrantly regulated. These include the sequestration of MBNL1, leading to misregulated splicing; sequestration of nucleolin, leading to reduced cellular rRNA; and sequestration of proteins of the siRNA machinery, resulting in the production of short silencing RNAs that affect gene expression. Second, we discuss the effect of expanded CAG repeats on the subcellular localization, transcription and translation of the CAG repeat mRNA itself. Here we focus on the MID1 protein complex that triggers an increased translation of expanded CAG repeat mRNAs and a mechanism called repeat-associated non-ATG translation, which leads to proteins aberrantly translated from CAG repeat mRNAs. In addition, therapeutic approaches for CAG repeat disorders are discussed. Together, all the findings summarized here show that mutant mRNA has a fundamental role in the pathogenesis of CAG repeat diseases.
Angiomotin prevents pluripotent lineage differentiation in mouse embryos via Hippo pathway-dependent and -independent mechanisms
Authors: Leung Chuen Yan , Zernicka-Goetz Magdalena
Published: August 2013

Cell identity is specified in the early mammalian embryo by the generation of precursors for two cell lineages: the pluripotent inner cell mass and differentiating trophectoderm. Here we identify Angiomotin as a key regulator of this process. We show that the loss of Angiomotin, together with Angiomotin-like 2, leads to differentiation of inner cell mass cells and compromised peri-implantation development. We show that Angiomotin regulates localization of Yap, and Yap-binding motifs are required for full activity of Angiomotin. Importantly, we also show that Angiomotin function can compensate for the absence of Lats1/2 kinases, indicating the ability of Angiomotin to bypass the classical Hippo pathway for Yap regulation. In polarized outside cells, Angiomotin localizes apically, pointing to the importance of cell polarity in regulating Yap to promote differentiation. We propose that both Hippo pathway-dependent and Hippo pathway-independent mechanisms regulate Yap localization to set apart pluripotent and differentiated lineages in the pre-implantation mouse embryo.
Analytical modelling of single‐phase stacked multicell multilevel converters exploiting Kapteyn (Fourier–Bessel) series
Authors: Dargahi Vahid , Dargahi Saeedeh
Published: August 2013

This study proposes a mathematical model for stacked multicell (SM) converters (SMCs), to be exploited in the analytic determination of the natural voltage balancing dynamics of the SMCs, that is, investigation of the start‐up behaviour, dynamic response and natural voltage balancing phenomenon. The crux of the proposed strategy is based on the closed‐form analytic solution derivation for the switching functions used in the switching of the SMCs operated under phase disposition (PD) and phase‐shifted carrier (PSC) pulse‐width modulation (PD–PSC‐PWM) technique. Hence, the suggested approach develops an analytic solution for the Fourier series and associated Fourier coefficients pertinent to the switching functions of the SMCs by obtaining the switching instants of the PD–PSC‐PWM modulator in terms of ‘Kapteyn series’ when the frequency of the triangular carrier waveform (fc) and that of the sinusoidal reference waveform (fr) have an integer ratio, that is, fcfr−1 = k, k ∈ ℕ. This strategy results into a model (‘first‐order differential equation based model’) which can be readily developed for the SMCs with any number of levels expediting the investigation of their performance. Numeric computation results of the proposed analytic model for the SMCs and simulation results as well as measurements taken from an experimental set‐up are presented in order to validate the suggested approach and derived model.
Maximum power point tracking of single‐ended primary‐inductor converter employing a novel optimisation technique for proportional‐integral‐derivative controller
Authors: El Khateb Ahmad , Abd Rahim Nasrudin , Selvaraj Jeyraj , Nasir Uddin Mohammad
Published: August 2013

This study presents an optimisation technique for proportional‐integral‐derivative (PID) controller to achieve maximum‐power‐point tracking (MPPT) of single‐ended primary‐inductor converter (SEPIC). A new weight function is developed to optimise the PID parameters based on gradient‐descent (GD) method by adding low‐pass filter term. The proposed optimisation method does not stick in the local minima, which happens frequently with the traditional weight function used in GD method, where the low‐pass filter term suppresses the noise and smooths the iteration process. The prototype of the proposed optimised PID‐based SEPIC converter for photovoltaic inverter applications is built using DSP‐based TMS320F28335. The performance of the proposed optimised PID‐based MPPT scheme is tested in both simulation and experiment at different operating conditions. A performance comparison of the proposed GD method with the conventional GD PID is also made in real‐time. It is found that the proposed optimised PID‐based SEPIC converter is superior to the conventional GD PID controller in terms of power transfer and efficiency. Furthermore, the proposed optimised PID controller for two‐level inverter can achieve a better total harmonic distortion (THD) level as compared to the multi‐level inverter frequently used by researchers for the same purpose.
Cascaded cross‐switched multilevel inverter in symmetric and asymmetric conditions
Authors: Farhadi Kangarlu Mohammad , Babaei Ebrahim , Sabahi Mehran
Published: August 2013

This study proposes and analyses a new cascaded multilevel inverter in both symmetric and asymmetric conditions. Firstly, the topology is presented in general form and then it is optimised. For any given number of voltage levels, the proposed topology reduces the number of switches. In the symmetric condition, the proposed topology offers capability of charge balance control method while reducing the number of switches. Also, unlike the other reduced switch topologies, the proposed topology does not increase the total standing voltage of the switches in comparison with the conventional cascaded H‐bridge (CHB) multilevel inverter. In the asymmetric condition, the proposed topology has highest output voltage resolution while keeping the total standing voltage equal to the CHB topology. In other words, in both symmetric and asymmetric conditions the number of switches in the proposed topology is lower than that of the CHB topology. However, both the proposed topology and also the CHB topology have the same total standing voltage on the switches. Other asymmetric topologies use higher number of switches and have higher total standing voltage in comparison with the proposed asymmetric topology. A modified phase‐shifted‐pulse width modulation is also presented for the proposed symmetric topology. The proposed topology is verified with simulation and experimental results.
Enhanced three‐phase multilevel inverter configuration
Authors: Odeh Charles Ikechukwu
Published: August 2013

This study reports a three‐phase multilevel inverter (MLI) topology. The MLI configuration generates voltage levels similar to the corresponding well‐known conventional diode‐clamped, flying capacitors and cascaded H‐bridge inverters but with fewer power circuit components and simplicity. By optimising the proposed switching patterns through analysis, the total harmonic distortion of the inverter output line voltage waveforms have been reduced. The validity of the proposed cascade MLI is verified through simulation and experiments.
Intelligent sensor fault‐tolerant control for variable speed wind electrical systems
Authors: Rajendran Santhi , Govindarajan Uma , Senthilvadivelu Shanthakumar , Uandai Sabura Banu
Published: August 2013

This study focuses on sensor fault‐tolerant control (FTC) for grid‐connected variable speed wind electrical systems (VSWES) to regulate active and reactive power flow through the grid. The closed‐loop performances of the VSWES massively depend on the precise voltage and current sensing. An abrupt failure or faulty measurement in one of the sensors may lead to system malfunction. To overcome this, the fault has to be detected and handled quickly. A simple and intelligent fault detection and isolation (FDI) algorithm is proposed in this study with which FTC is implemented for VSWES. The FDI is derived from model‐based observer schemes, which are developed using neural networks. The wind electrical system with permanent magnet synchronous generator and matrix converter is adopted here. The grid voltage‐oriented control scheme is developed for power flow regulation. The simulation and experimental results are presented to illustrate the effective functionality of the system.
Switching algorithm for single Z‐source boost multilevel inverter with ability of voltage control
Authors: Banaei Mohamad Reza , Dehghanzadeh Ali Reza , Fazel Ali , Oskouei Aida Baghbany
Published: August 2013

This study proposes a new topology of cascaded transformer‐based multilevel inverter using single Z‐source. The suggested circuit consists of only one Z network and one DC voltage source; as a result installation area is reduced. In this topology, the output voltage amplitude is not limited to DC voltage source similar to traditional cascaded transformer‐based multilevel inverter and can be increased with Z network shoot‐through state control flexibly. Besides, the same as traditional Z‐source inverter, it is more reliable against short circuit. Also, a particular switching algorithm has been suggested for presented inverter, which can obtain total harmonic distortion (THD) of output voltage nearly constant for different boost ratio. Moreover, as compared to traditional Z‐source inverter, the THD of output voltage is decreased in the suggested topology. The performance of proposed inverter and switching algorithm are validated with simulation results using MATLAB/SIMULINK software and experimental results based PCI‐1716 data acquisition system.
Zero‐Voltage‐Transition auxiliary circuit with dual resonant tank for DC–DC converters with synchronous rectification
Authors: Yang Hong‐Tzer , Liao Jian‐Tang , Cheng Xiang‐Yu
Published: August 2013

DC–DC converters are needed to supply power with high efficiency in various applications in industry. However, the conventional DC–DC converters cannot achieve higher efficiency mostly owing to the switching and conduction losses. On the basis of existing topologies, in this study a novel ZVT auxiliary circuit with dual resonant tank for the DC–DC converters with synchronous rectification (SR) is proposed. The proposed ZVT auxiliary circuit aims at reducing losses of conventional DC–DC converters by using zero‐voltage‐switching, zero‐current‐switching and SR with reduced reverse recovery time of junction diodes. To verify the proposed circuit, a Buck converter integrated with the proposed dual resonant tank is implemented in this study. The simulated and experimental results obtained have demonstrated that the proposed dual resonant tank can be practically implemented in conventional DC–DC converters to provide better performance as compared with existing topologies.
Multilevel inverter based on cascaded association of Buck EIE inverters
Authors: Costa Natalia , Melo Fernando , de Freitas Luiz , Coelho Ernane , Freitas Luiz C.G.
Published: August 2013

The multilevel inverters are pointed in the literature as one of the most suitable solutions for high‐power applications, in medium and high voltage levels. These inverters are based on the association of converters, either in parallel or in series, aiming at processing smaller amount of the total output power in each converter. Generally, the output voltage and/or current are a staircase waveform and the output voltage has low harmonic distortion because of the used passive filters and/or modulation techniques. In this context, a novel approach on cascaded multilevel inverters is presented in this study. The proposed topology is based on the cascaded association of Buck EIE inverters, developed from the EIE active commutation cell. The output voltage is totally controlled and it follows a desired reference signal, which assures a low harmonic distortion without the necessity of using passive filters on the output of the converter. The level of voltage stress over the power semiconductor devices, especially switches and diodes, are kept low even for high voltage applications. Detailed circuit description is given as well as a complete theoretical analysis. The mathematical model for the three‐level Buck EIE inverter is also presented and, in order to confirm the operation of the proposed topology, experimental results are here addressed.
Improved space‐vector modulation technique for common mode currents reduction
Authors: Cacciato Mario , De Caro Salvatore , Scarcella Giuseppe , Scelba Giacomo , Testa Antonio
Published: August 2013

Modified space‐vector modulations (MSVMs) that reduce the variations of common mode voltage (CMV) for decreasing common mode currents (CMCs) are a low cost interesting approach. Unfortunately the lack of full utilisation of the DC bus voltage is a severe drawback that can limit the exploitation of such modulation techniques, unless special overmodulation methods are adopted. In this study, some solutions are presented that make a trade‐off between the DC bus voltage exploitation and CMCs reduction and make MSVMs appealing to most electrical drives on the market. Furthermore, the influence of dead time in CMV generation is considered thus modifying the switching patterns according to the sign of the load currents. Experimental results are presented in order to confirm the feasibility of the proposed approach.
Bridgeless electrolytic capacitor‐less valley‐fill AC/DC converter for offline Twin‐Bus light‐emitting diode lighting application
Authors: Ma Hongbo , Zheng Cong , Yu Wensong , Gu Bin , Lai Jih‐Sheng (Jason) , Feng Quanyuan
Published: August 2013

To match the key features of light‐emitting diode (LED) lighting source and further save power, LED lighting driver also requires long life, while maintaining high efficiency, high power factor, pulse‐width modulation dimming and low cost. However, a typical LED lighting driver has the following drawbacks: (i) utilise bulky electrolytic capacitor as storage capacitor with short lifetime; (ii) employ a low‐frequency diode bridge as the rectifier cell; and (iii) engage multiple stages cascade structure for multiple LED strings. To overcome the aforementioned shortages, this study proposed a bridgeless electrolytic capacitor‐less AC/DC converter for offline LED lighting application. In the proposed converter, the conventional diode rectified bridge is replaced by Totem‐pole bridgeless configuration for reducing the number of semiconductors in the line‐current path. Meanwhile, the valley‐fill circuit is introduced to further reduce the capacitor size. As comparison to its counterpart, the proposed circuit requires only one quarter of the capacitor energy when considering the energy amount (CV2) as the capacitor sizing criterion. Furthermore, the isolation type of the studied circuit is compatible with Twin‐Bus configuration for achieving higher overall system efficiency. Finally, the experimental results, taken from a laboratory prototype rated at 50 W, are presented to verify the effectiveness of the proposed converter.
Power loss analysis of active clamp forward converter in continuous conduction mode and discontinuous conduction mode operating modes
Authors: Xu Shen , Zhang Taizhi , Yao Yunpeng , Sun Weifeng
Published: August 2013

In order to improve the light‐load efficiency of active clamp forward converter with synchronous rectifier (SR), power loss analysis of the converter operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are presented in this study. The light‐load efficiency of normal ACF converter with SR is low because the output inductor current can go negative when operating in CCM. Considering the fixed frequency control only, to shift the converter's operating mode from CCM to DCM at a critical point of output current at light‐load is a solution for efficiency improvement. Based on the CCM and DCM power dissipation models proposed in this study, the power loss characteristics of the converter are analysed, and the critical shift point of output current can be derived, which has also been verified by an experimental prototype.
Family of high‐boost Z‐source inverters with combined switched‐inductor and transformer cells
Authors: Nguyen Minh‐Khai , Lim Young‐Cheol , Park Sung‐Jun , Shin Duck‐Shick
Published: August 2013

This study proposes a new family of high‐boost Z‐source inverters (ZSIs) with combined switched‐inductor and transformer cells. By changing the transformer turn ratio, the number of switched‐inductor cells and shoot‐through duty cycle, the proposed inverter produces high voltage gain. Compared with the conventional high‐boost ZSI topologies for the same input and output voltage, the proposed inverter uses a higher modulation index to improve the output waveform. An alternate‐cascaded technique is applied to the proposed inverter to distribute the stresses on the passive components. This study presents the operating principles and analysis. To verify the performance of the proposed inverter, simulation and experimental results are shown with various transformer turn ratios.
One zero‐voltage‐switching three‐transistor push–pull converter
Authors: Yuan Yisheng , Wu Qunfang
Published: August 2013

One three‐transistor push–pull (TTPP) converter is proposed in this study. In this TTPP converter, an extra transistor is inserted between the input power supply and midpoint of two primary windings. On the secondary side, a saturable inductor and an extra freewheeling diode are employed. Adopting the proposed pulse‐width modulation method for three power switches, two original transistors can achieve zero‐voltage‐switching (ZVS) easily in a wide range of load current, the extra transistor can also realise ZVS assisted by the saturable inductor. Each operation mode of the proposed TTPP converters is discussed in detail. The soft‐switching conditions are explained. One 83.3 kHz, 800 W prototype has been built. Its peak efficiency reaches 94.87%. The experimental result is provided to verify the analysis.
Extension of particle filters for time‐varying target presence through split and raw measurements
Authors: Danaee M.R. , Behnia F.
Published: August 2013

Target tracking through particle filter (PF) for time‐varying presence of a target is compared for thresholded and non‐thresholded measurements, where in both cases a track produces more than one measurement. To that end, thresholded split measurements PF along with non‐thresholded measurements, sequential importance resampling PF (SIR PF) and auxiliary variable PF (AV PF) are extended to cope with time‐varying target presence. Simulations show superiorities in working through non‐thresholded measurements. Furthermore, they surprisingly demonstrate that non‐thresholded measurements SIR PF leads to less root‐mean‐square position estimation error than non‐thresholded measurements AV PF in case of uncertain target presence and unclear measurements origin besides dynamic model mismatching.
Target tracking via multi‐static Doppler shifts
Authors: Ristic Branko , Farina Alfonso
Published: August 2013

This article studies the problem of joint detection and tracking of a target using multi‐static Doppler‐only measurements. The assumption is that in the surveillance volume of interest a single transmitter of known frequency is active with multiple spatially distributed receivers collecting and reporting Doppler‐shift frequencies to the data fusion centre. The measurements are not only affected by additive noise but also contaminated by false detections and missed detections. The study develops for this application of a multi‐sensor Bernoulli particle filter with information gain‐driven receiver selection. The simulation results indicate robust performance of the proposed Bernoulli particle filter.
Multiband time‐of‐arrival positioning technique using an ultra‐high‐frequency bandwidth availability model for cognitive radio
Authors: Thomas Robin Rajan , Maharaj Bodhaswar T. , Zayen Bassem , Knopp Raymond
Published: August 2013

In this study, the authors present a multiband time‐of‐arrival (TOA) positioning model and validate the performance in a practical dynamic spectrum access scenario according to results obtained from an ultra‐high‐frequency (UHF) spectrum occupancy measurement campaign. The statistical analysis of the measured data shows a distinguishable difference between the unoccupied and occupied portion of the UHF band. The bandwidth availability for the UHF band is shown to follow a Gaussian distribution according to the measurement results. The positioning model is verified using the non‐linear least squares, linear least squares and two‐step maximum‐likelihood location estimation algorithms. The root‐mean‐square error (RMSE) performance evaluation of the proposed model revealed the advantage of utilising five discrete bands to perform TOA estimation, especially in poor signal‐to‐noise ratio (SNR) conditions ranging from − 10 to 0 dB. At a fixed SNR of 0 dB, an average RMSE improvement of 74 and 82% was observed for a double‐ and triple‐band system when compared with a conventional single‐band TOA system. This particular positioning technique can enable improved location estimation in a dynamic spectrum access environment.
Cramer–Rao bound of parameters estimation and coherence performance for next generation radar
Authors: Sun Palin , Tang Jun , He Qian , Tang Ba , Tang Xiaowei
Published: August 2013

In this study, a general signal‐processing architecture is proposed for next generation radar (NGR). When the NGR works in MIMO mode, we derive the closed‐form Cramer–Rao bound of the estimation of coherent‐processing parameters, which include the time‐delay differences and phase synchronisation errors among different apertures. When the NGR turns to work in fully coherent mode, assuming the time‐delay differences are ideally compensated, the authors present the closed‐form signal‐to‐noise ratio (SNR) gain and analyse the SNR gain loss of the NGR because of inaccurate phase synchronisation errors.
Compressed sensing for SAR‐based wideband three‐dimensional microwave imaging system using non‐uniform fast Fourier transform
Authors: Kajbaf Hamed , Case Joseph T. , Yang Zengli , Zheng Yahong Rosa
Published: August 2013

A new compressed sensing (CS) image reconstruction method is proposed for high‐resolution wideband three‐dimensional synthetic aperture radar (SAR) imaging systems. In contrast to existing CS SAR methods that employ only a forward SAR transform in pre‐ or post‐processing, the proposed method employs both forward SAR and reverse SAR (R‐SAR) transforms in each CS iteration to improve the quality of reconstructed images. This study proposes a simple and elegant truncation repair method to combat the truncation error and utilises non‐uniform fast Fourier transform to reduce the SAR and R‐SAR transform errors, thereby ensuring the convergence of the CS algorithm and improving the quality of the reconstructed images. The proposed CS SAR method is applied to microwave and millimeter wave imaging systems for non‐destructive evaluation of materials embedded in stratified media. Three different specimens under test are measured by conventional uniform sampling and by random under‐sampling with 20% or 30% spatial points of the uniform sampling. The reconstructed images show that, albeit having much less measurement points, the proposed CS method achieves better image quality and lower background artefacts than the images reconstructed from the fully‐sampled uniform measurements.
High‐precision hyperboloid location method using passive time‐difference‐of‐arrival measurements
Authors: Lei Wenying , Chen Baixiao
Published: August 2013

The authors consider the minimum square error formulation of the three‐dimensional target location problem and provide an efficient solution for this minimisation problem. Two target location scenarios are investigated and it has been found that the convexity of the nonlinear least squares problem depends on the geometric relationship between the receivers and the target. The authors discover that the non‐linear least squares problem is not always non‐convex. The corresponding non‐linear least squares problem is non‐convex and sensitive to initial value only when the three time‐difference‐of‐arrival location hyperboloids form two intersections. The convergence of the iterative method is proved when the objective function is convex in the location region. Simulation results demonstrate the effectiveness of the proposed method both in non‐convex and convex scenarios, when a proper relative simple initial value is given.
Radar information creation with use of a simulation environment
Authors: Hamtil Ivan , Sebela Miroslav , Stefek Alexandr
Published: August 2013

In this study, there are presented theoretical basics for the stochastic constructive simulation of surveillance radar sensors as a generator of radar information with the stochastic character. To do this, the mathematical model of the creation of radar information is performed. The mathematical model is afterwards presented in the form of an algorithm flowchart for the process of the radar information creation. The model will be applied as part of a simulator for the staff training in the Czech Air Force operational centres.
Parametric analysis of ballistic target‐tracking problem by multiple model approach
Authors: Reali Fabrizio , Palmerini Giovanni B. , Farina Alfonso , Graziano Antonio , Giompapa Sofia
Published: August 2013

Radar tracking of a ballistic target is a topic presenting very complex issues especially when the characteristics of the objects flying into the Earth's atmosphere are poorly known. As the target identification is required to obtain good performance, a technique frequently employed in the practical applications is the multiple model filter. This study, thought the increasing interest for this class of estimators, aims to identify the key parameters of the problem by making recognisable their effects on the solution. Thus – along with the ideal operative conditions – the relative geometry target‐sensor, the presence of missing plots, the measurement uncertainties and the credibility of filter predictions are investigated. In order to have a strict benchmark of evaluation the multiple model approach performance is compared with the optimal estimate given by posterior Cramér–Rao lower bounds.
Temperature and impurity effects of the polaron in an asymmetric quantum dot
Authors: Shan Shu-Ping , Liu Ya-Min , Xiao Jin-Lin
Published: August 2013

Temperature and impurity effects of the ground state energy and the ground state binding energy in an asymmetric quantum dot are studied here by using the linear combination operator method. It is found that the ground state energy and the ground state binding energy increase with increasing temperature. The ground state energy is a decreasing function of the Coulomb bound potential, whereas the ground state binding energy is an increasing one.