Extended High Efficiency Computed Tomography with Optimized Recursions

This paper presents a high-reliability single-phase transformerless grid-connected inverter that utilizes superjunction MOSFETs to achieve high efficiency for photovoltaic applications. The proposed converter utilizes two split ac-coupled inductors that operate separately for positive and negative half grid cycles. This eliminates the shoot-through issue that is encountered by traditional voltage source inverters, leading to enhanced system reliability. Dead time is not required at both the high-frequency pulsewidth modulation switching commutation and the grid zero-crossing instants, improving the quality of the output ac-current and increasing the converter efficiency. The split structure of the proposed inverter does not lead itself to the reverse-recovery issues for the main power switches and as such superjunction MOSFETs can be utilized without any reliability or efficiency penalties. Since MOSFETs are utilized in the proposed converter high efficiency can be achieved even at light load operations achieving a high California energy commission (CEC) or European union efficiency of the converter system. It also has the ability to operate at higher switching frequencies while maintaining high efficiency. The higher operating frequencies with high efficiency enables reduced cooling requirements and results in system cost savings by shrinking passive components. With two additional ac-side switches conducting the currents during the freewheeling phases, the photovoltaic array is decoupled from the grid. This reduces the high-frequency common-mode voltage leading to minimized ground loop leakage current. The operation principle, common-mode characteristic and design considerations of the proposed transformerless inverter are illustrated. The total losses of the power semiconductor devices of several existing transformerless inverters which utilize MOSFETs as main switches are evaluated and compared. The experimental results with a 5 kW prototype circuit show 99.0% CEC efficiency and 99.3% peak efficiency with a 20 kHz switching frequency. The high reliability and efficiency of the proposed converter makes it very attractive for single-phase transformerless photovoltaic inverter applications.

High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material

Elevada eficiencia térmica y mínimas emisiones contaminantes impuestas por las restrictivas normativas anticontaminación en motores alternativos representan el principal objetivos de los fabricantes de motores. \nLa estrategia de combustión diésel convencional es ampliamente utilizada en el mundo gracias a su excelente economía en el consumo de carburante. Esta estrategia permite operar con mezclas pobres de combustible y aire proporcionando elevada eficiencia térmica. Además, este tipo de combustión puede ser aplicada desde motores tanto para vehículos ligeros como en motores marinos. Sin embargo, este proceso de combustión conlleva a la generación de elevadas emisiones de NOx y emisiones de partículas (comúnmente llamado hollín en los diésel), siendo imposible reducir ambos contaminantes de forma simultánea. Por tanto, los fabricantes han incorporado sistemas de post-tratamiento con el objetivo de cumplir con las normativas de emisiones, cuya intención es la de proveer emisiones más limpias y elevada eficiencia. Por el contrario, este tipo de sistemas para mitigar las emisiones contaminantes incrementan la complejidad del motor dado el complejo proceso llevado a cabo durante el post-tratamiento y una aumento en los costes tanto de producción como operativos a lo largo del ciclo de vida del motor. La comunidad científica continua desarrollando soluciones alternativas a la combustión diésel convencional manteniendo los beneficios de este proceso de combustión mientras que las emisiones son reducidas (principalmente NOx y hollín). \nLa comunidad científica ha encontrado en las estrategias de combustión de baja temperatura un proceso de combustión capaz de proporcionar elevada eficiencia térmica y emisiones ultra bajas de NOx y humo. En este sentido, la revisión bibliográfica dice que estos tipos de combustión permiten la reducción simultánea de ambas emisiones, rompiendo así el tradicional "trade-off" existente en la combustión diésel convencional. Sobre todas las estrategias, la que muestra un potencial superior es la estrategia conocida como combustión dominada por la reactividad del combustible. Este proceso de combustión se caracteriza por emplear dos combustibles, siendo capaz de solucionar los principales problemas de las estrategias de baja temperatura tales como el fasado de la combustión. Sin embargo, esta estrategia de combustión también presenta algunos inconvenientes como el elevado nivel de monóxido de carbono e hidrocarburos inquemados a baja carga y elevado gradiente de presión y presión en cámara a elevada carga que limitan el rango de operación. \nEl objetivo general de la presente investigación es proveer de una estrategia de combustión "dual-fuel" capaz de operar sobre todo el rango de operación de un motor proporcionando igual o mejores eficiencia térmica que el diésel convencional y emisiones ultra bajas de NOx y humos. Adicionalmente, esta investigación implica una exploración delas emisiones de las partículas del concepto de combustión ya que el número de partículas se encuentra actualmente regulado por la normativa anticontaminante. \nEl proceso de combustión que responde a este objetivo es "Dual-Mode Dual-Fuel". Este concepto de combustión emplea dos combustibles y cambia de combustión premezclada a baja carga a combustión de naturaleza difusiva a plena carga. Con el deseo de explorar las capacidades de la estrategia de combustión, se han empleado dos configuraciones de "hardware" y se ha realizado un estudio de la distribución por tamaños de las partículas. \nFinalmente, considerando los principales resultados de la investigación, el último capítulo pretende resumir las principales bondades del concepto de combustión así como sus limitaciones y trabajos futuros.

We report that we can achieve extremely high separation efficiencies using a narrow, open, tubular (NOT) column for liquid-chromatographic separations, and we can carry out these separations under an elution pressure of no more than 50 bar. To improve the separation efficiency in packed-column liquid chromatography, one of the most effective approaches is to reduce the monodispersed-particle sizes. A direct consequence of reduced particle size is an increased elution pressure. High efficiencies have been obtained in ultrahigh-performance liquid chromatography (UPLC) using 1-2 μm or even submicron particles, and high elution pressures (greater than 1000 bar) are commonly used to carry out these separations. Open, tubular (OT) columns have been predicted to be the most efficient columns for high-efficiency liquid-chromatographic separations, as long as the column diameter is sufficiently small (1-2 μm). However, high efficiencies have not yet been publically reported, possibly because of the challenges (such as picoliter-volume detection, nanocapillary-column preparation, low sample loadability, etc.) of utilizing 1-2 μm diameter capillaries. In this paper, we show how we overcame these problems and achieved extremely high separation efficiencies using a 2 μm inner diameter capillary. We see 200+ apparent peaks with a peak capacity of 810 within 54 min when separating a sample from trypsin-digested cytochrome C, and we count 440 apparent peaks with a peak capacity of 1640 within 172 min when separating a sample from pepsin/trypsin-digested Escherichia coli cell lysate.

Achieving high phosphorescence efficiency and photo-activated ultralong organic phosphorescence (UOP) based on the same molecule remains a formidable challenge. Here, a concise strategy is proposed to obtain highly efficient and photo-activated RTP by doping aromatic heterocyclic derivatives into different polymers. Aromatic heterocyclic derivatives are doped into PAM, PVA, or PAA polymers to produce high phosphorescence efficiency. Impressively, the highest phosphorescence quantum yield can reach up to 66.2% at room temperature, which can be attributed to isolating the chromophore to reduce the excimer and the rigid environment from the polymer to restrict the non-radiative transitions. In addition, phosphorescence emission color can be tailored from green to deep blue by varying the guests. After aromatic heterocyclic derivatives are doped into PDMA or PVP, the phosphorescence lifetime is prolonged from 1.2 to 578.6ms. These polymers are successfully applied to multicolor displays and high-level information storage. This work provides a reasonable strategy to develop highly efficient and photo-activated RTP materials based on the same molecule.

The mechanisms of achieving high phase efficiency of a meta-surface are researched and analyzed systematically. For a reflective element, an electrically small size, a complete phase-shift range of more than 360°, and also a smooth phase response play an essential role in determining the high phase efficiency. Based on the design principle, an excellent element is proposed consisting of an isotropic three-turn square-ring resonator (ITSR) on a single-layer slab. The characterizations of the ITSR element are investigated in depth through theoretical calculation, comparative analysis, and electromagnetic (EM) simulation. A focusing meta-lens, with a parabolic phase distribution, is well optimized using 14 × 14 elements. Good focusing effect is demonstrated within a wide bandwidth of more than 1 GHz. Exciting the meta-lens with a waveguide feed antenna at the focus, a high-efficiency reflectarray antenna is designed, which shows a series of advances, such as high aperture efficiency of better than 70%, 1-dB gain bandwidth wider than 13.07%, and also competitive radiation gain. The proposed strategy opens an avenue to new types of high-efficiency RMSs and reflectarray antennas with enhanced radiation characteristics.

Green hydrogen produced by water splitting using renewable electricity is essential to achieve net-zero carbon emissions. Present water electrolysis technologies are uncompetitive with low-cost grey hydrogen produced from fossil fuels, limiting their scale-up potential. Disruptive processes that decouple the hydrogen and oxygen evolution reactions and produce them in separate cells or different stages emerge as a prospective route to reduce system cost by enabling operation without expensive membranes and sealing components. Some of these processes divide the hydrogen or oxygen evolution reactions into electrochemical and chemical sub-reactions, enabling them to achieve high efficiency. However, high efficiency has been demonstrated only in a batch process with thermal swings that present operational challenges. This work introduces a breakthrough process that produces hydrogen and oxygen in separate cells and supports continuous operation in a membraneless system. We demonstrate high faradaic and electrolytic efficiency and high rate operation in a near-neutral electrolyte of NaBr in water, whereby bromide is electro-oxidized to bromate concurrent with hydrogen evolution in one cell, and bromate is chemically reduced to bromide in a catalytic reaction that evolves oxygen in another cell. This process may lead the way to high-efficiency membraneless water electrolysis that overcomes the limitations of century-old membrane electrolysis.

CO2 bubble-assisted in-situ construction of mesoporous Co-doped Cu2(OH)2CO3 nanosheets as advanced electrodes towards fast and highly efficient electrochemical reduction of nitrate to N2 in wastewater

We proposed a novel strategy to design a deep subwavelength metasurface with full 2π transmission phase modulation and high transmission efficiency by applying resonators with interfering Fano resonance. Theoretical investigation demonstrates that the transmission efficiency of the resonators depends on the direct transmission coefficient, direct reflection coefficient, and Q factor. When an impedance layer is added in the resonators, the direct transmission and direct reflection coefficients can be facilely manipulated so that the span of the transmission phase around the resonance frequency can be extended to 2π. As a result, we can continuously adjust the transmission phase from 0 to 2π through changing the geometric parameters of the resonators and construct a deep subwavelength metasurface with the resonators to manipulate the transmission wave with high efficiency. We also find that a layer of grating can be used as the impedance layer to change direct transmission and direct reflection in the actual design of the metasurface. The proposed strategy may provide effective guidance to design a deep subwavelength metasurface for controlling a transmitted wave with high efficiency.

Ceramic/polymer nanocomposites have shown great potential in high energy storage density capacitors for pulsed power applications. However, due to the difference in surface energy between inorganic fillers and polymers, the discharge energy density and efficiency of nanocomposites are limited. In this article, the BaTiO3 (BT) nanowires (NWs) modified with dopamine (Dopa) was introduced into aromatic polythiourea (ArPTU) polymer matrix as composite for high-performance dielectrics. This is a new path about the introduction of a high dielectric constant ceramic into high dipole moment linear polymers (HDMLP), which produces the polymer composite with high energy storage density and high discharge efficiency. The composite ArPTU/BT NWs shows an energy density of 7.5 J cm−3 and high efficiency more than 90% is obtained under an electric field of 250 MV m−1. It also has been found that the modification of BT NWs with the Dopa reduces the dielectric loss of composite effectively due to the good synergistic effective between ArPTU and BT NWs, and high stability of composite for energy storage is also achieved. This work provides an effective solution for achieving high energy storage density and high discharge efficiency in polymer dielectrics for practical capacitor applications.

A supercritical carbon dioxide (S-CO2) gas turbine can generate power at a high cycle thermal efficiency, even at a modest temperature level of 500–550°C. Its high thermal efficiency is attributed to markedly reduced compressor work at the vicinity of the critical point. Furthermore, the reaction between Na and CO2 is milder than that between H2O and Na. Consequently, a more reliable and economically advantageous power generation system is achieved by coupling with a Na cooled fast reactor. In a typical design, the reactor thermal power, a turbine inlet pressure and an inlet temperature are, respectively, 600 MW, 20 MPa and 527°C. In the S-CO2 gas turbine system, a partial cooling cycle is used to compensate a difference in heat capacity for the high-temperature – low-pressure side and the low-temperature – high-pressure side of the recuperators to achieve high cycle thermal efficiency. The flow is divided into two streams before the precooler. One stream goes to recuperator 2 via a main compressor (MC); the other goes to recuperator 1 via a bypass compressor (BC). The performance and integrity of these two compressors are crucial. As described herein, an aerodynamic design of BC is given. The inlet temperature, inlet pressure, exit pressure and mass flow rate are, respectively, 77°C, 8 MPa, 20 MPa and 1392 kg/s. The salient features of this compressor are its compact size and a large bending stress caused by the large mass flow rate. The number of stages is numerous associated with the large enthalpy rise compared with MC. To achieve as high efficiency as possible, not a centrifugal type but an axial type is examined first. The aerodynamic design was conducted using one-dimensional design method, where the loss model of Cohen et al. is used. Its aerodynamic design enables the use of several stages and provides total adiabatic efficiency of 21 and 87%, respectively. Then, CFD analysis was conducted using “FLUENT”. Blade shapes were prepared based on flow angles and chord length obtained in the aerodynamic design. The CO2 properties in a fluid computer dataset “PROPATH” were used. The features of gas velocity distribution and pressure distribution were confirmed to the fundamental knowledge. The value of the calculated flow rate coincided very well with that of the design.

This study aimed to describe the limitations in information-processing skills observed among persons with schizophrenia performing daily tasks and to explore whether subgroups of participants have similar profiles based on these functional limitations. Eighty-two participants with schizophrenia living in the community were assessed during their performance of a daily activity (meal preparation). Measures included a performance-based assessment for evaluating information-processing skills-the Perceive, Recall, Plan, and Perform System of Task Analysis-community functioning and symptom assessments, and neuropsychological tests from the Cambridge Neuropsychological Test Automated Battery. Research participants were classified as having high efficiency or low efficiency according to their score on the performance-based assessment and were compared on the functional, cognitive, and symptoms variables. Participants committed various errors, and functional limitations, namely problematic information-processing skills in the perceive, recall, and plan quadrants, were observed during the daily task performance. Participants from the high-efficiency group were more independent in their living skills and more successful in attaining residential independence compared with participants from the low-efficiency group. The only cognitive test that differentiated both groups was the visuospatial associative learning test. No differences were found in the severity of symptoms. Findings suggest that both performance in a daily task and memory-and specifically associative learning capacity-provide key information for the level of residential independence. Interventions aiming for the efficient use of information-processing skills during daily tasks among persons with schizophrenia should be carried out accordingly.

Daily Functioning and Information-Processing Skills Among Persons With Schizophrenia

Data Transmission plays an important role in the digital world. In here, We are using Cognitive Radio(CR) a concept on Wireless Sensor Networks(WSN) which is being used as an intelligent wireless Communication Technology having unique Capabilities of monitoring spectrum bands and detecting available channels to enable the usage of statically allocated spectrum Furthermore, by dynamically adjusting its operating parameters, it can utilize available channels and to attack the upcoming spectrum crunch issue. Cognitive Radios can be used to find unused licensed spectrum and it can be utilized by secondary users without causing any interference to licensed users. Existing technologies used in cognitive radio include energy sensing, spectrum databases, and spectrum sensing using pilot channels. In small networks, transmission of small packet size can be transmitted with high efficiency without delay, whereas transmission of large data packets can cause data corruption, data packet corruption and may require retransmission over higher frequency channels. To avoid this type of interference, users need higher efficiency and wider bandwidth for efficient transmission. Here we use the technique of momentum search algorithms working on the law of conservation of momentum and the law of conservation of kinetic energy. Data transferred using this method is always unaltered. The transmitted data is split into fixed-size 64-bit packets. And the channel selection will be changed accordingly for higher channel selection efficiency for lossless data transmission. The rules of the Momentum Search algorithm allow users to transmit larger data packets with higher efficiency with the same level of interference as the primary user (PU). This proposal shows how to achieve the highest level of data transmission performance using a cognitive wireless network based on a Momentum search algorithm.

The predatory mirids Macrolophus pygmaeus Ramber and Nesidiocoris tenuis Reuter (Heteroptera: Miridae) are used for the biological control of Tuta absoluta Meyrick (Lep.: Gelechiidae) and other pests in tomato greenhouses. The functional response of 1 (young) and 10 (old) days old adult females and males of M. pygmaeus and N. tenuis on eggs of T. absoluta, was determined on tomato at two temperatures (20° and 25°C) and LD 16:8 and found to be Type II. M. pygmaeus females exhibited higher predation efficiency, than males at both tested temperatures. Young M. pygmaeus females had a higher efficiency than old ones, whereas males had a low efficiency irrespective of age. The predation efficiency of N. tenuis was high (but lower than M. pygmaeus) in both young females and males, although old females had a higher efficiency than the respective males. Our results show that the two predatory species have different functional response characteristics to their prey depending mainly on sex and age which may affect their role as biological control agents.