New Multilevel Mixed Topology Development to Improve Inverter Robustness for Domestic Photovoltaic Installations

Multilevel inverters are well used in grid connected domestic photovoltaic applications because of their ability to generate a very good quality of waveforms, reducing switching frequency, and their low voltage stress across the power devices. However, this kind of inverter has to be modified to both limit common-mode currents and improve the robustness of the system. This paper presents a new mixed 5-level inverter that meets these challenges. The operating principle of the converter is proposed. Several experimental measurements are described to validate this new concept. The output voltage and current and the THD of the output voltage are particularly discussed.

Characterization and Modeling Home Power Grid Topologies in PLC Broadband

Home power outlets can be connected in various topologies： derivation, star, cascade. This paper firstly describes the intrinsic behavior of the transfer function of these basic topologies. Secondly, the channel capacities of the three topologies are compared to check if there is a more favorable topology. Many deterministic modeling methods have been developed to compute the transfer function of power line networks but the given examples in the studies correspond only to the derivation topology with branches connected to the direct path between transceivers. Thirdly, this paper evaluates the ability of common modeling methods （multipath and chain matrices） to compute accurately the transfer function of any topology. Modeling the derivation topology with ＂secondary＂ branches and the star topology is shown to be inappropriate with chain matrices based method. Indeed, this method is very sensitive to the uncertainty of the second parameters of the power cables and this induces considerable fading shifts for those topologies. Multipath modeling method produces results agreeing with measurements for any topology.

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Capacitive Micromachined Ultrasonic Transducer (CMUT) technology, which has been widely studied in the field of medical imaging, possesses strong design flexibility due to its manufacturing process. Many applications could benefit from this unique feature, especially those that require different operating ultrasonic frequencies. This article reports on the characterization of the therapeutic low-frequency field provided by an ultrasound-guided focused ultrasound CMUT probe that is connected to a custom ultrasonic scanner for hyperthermia applications. The study begins by mapping the focused ultrasonic beam in the vicinity of the focal spot and a parametric analysis providing the maximum peak-to-peak (PTP) pressure delivered by the probe under different acoustic conditions. The measured maximum PTP pressure at the targeted operating frequency of 1 MHz is 3 MPa, with a maximum of 3.6 MPa at 1.25 MHz. Based on an in vitro setup found in the literature, the temperature elevation at the focal point was measured, showing results in agreement with the targeted applications (max. ΔT = 7.5°C). The article concludes with a reliability study considering the delivered pressure and the self-heating of the CMUT probe: the results show the good stability of the pressure amplitude over 1.8 × 109 cycles at a duty cycle of 40%, with a moderate internal heating of 3°C.

Electromagnetic Coupling Modeling of Microstrip Lines Used in Switching Power Supplies

One of the major problems in electromagnetic compatibility is the interference due to erosstalk on the PCB （printed circuit board） in the SiP （system-in-package） technology. In this work, electromagnetic coupling modeling of coupled microstrip lines used in switching power supplies is presented. The different blocks which are connected through buses realized on PCBs will be considered as a coupled transmission line. The coupled microstrip transmission lines are modeled by a mathematical model based on the MoM （method of moments）. This model is done by Maflab routines. A SPICE （simulation program with integrated circuit emphasis） model is proposed for the prediction of the NEXT （near^crosstalk） and the FEXT （far-crosstalk） at the terminals of the command line. This command line is often victim of electromagnetic interference emitted by a transmission line source close. Some solutions against crosstalk depending on the physical parameters of the coupled transmission lines are proposed.

Indoor Narrowband Power Lines Channel Characterization

Power line is an efficient media for home area networking communication scenarios. However, it is not designed to transmit data. This causes several perturbations phenomenon for communications technologies over the power cables. This work presents an investigation of the indoor narrowband power lines channel behavior. The load, the transmission line length and the network topology impact are studied using a simple network. A channel response measure campaign has been realized in 13 sites. The channel capacity has been used for channel classification. The measures were classified into 5 classes. It is shown that channel response is mainly impacted by the load impedance. The class distributions are more impacted by the nature of appliances connected into the indoor network.

Development and Static Mode Characterization of a New Low-Loss AC Switch Based on Super-gain BJT

This paper deals with an innovative low-loss AC switch, named as TBBS （transistor based bidirectional switch）, based on the association of super-gain BJTs developed by the GREMAN laboratory. The main characterization results of the super-gain BJT are reminded to identify the key parameters that are essential to build the TBBS. A complete characterization database in static mode of this new AC switch is discussed. In particular, its forward and reverse-biased features have been measured to see the evolution of the DC current gain as a function of the current density. The TBBS makes sense when using the super-gain BJT （bipolar junction transistor） in reverse mode. It means that the reverse DC current gain has to be sufficient （at least higher than l compared with the conventional BJT one）. This new AC switch is bidirectional in current and voltage, totally controllable （turn-on and turn-off） and the most attractive solution in terms of on-state power losses. Further, its manufacturing process is as easier as existing device such as triac.

A Highly Efficient Algorithm for Phased-Array mmWave Massive MIMO Beamforming

With the rapid development of the mobile internet and the internet of things(IoT),the fifth generation(5G)mobile communication system is seeing explosive growth in data traffic.In addition,low-frequency spectrum resources are becoming increasingly scarce and there is now an urgent need to switch to higher frequency bands.Millimeter wave(mmWave)technology has several outstanding features—it is one of the most well-known 5G technologies and has the capacity to fulfil many of the requirements of future wireless networks.Importantly,it has an abundant resource spectrum,which can significantly increase the communication rate of a mobile communication system.As such,it is now considered a key technology for future mobile communications.MmWave communication technology also has a more open network architecture;it can deliver varied services and be applied in many scenarios.By contrast,traditional,all-digital precoding systems have the drawbacks of high computational complexity and higher power consumption.This paper examines the implementation of a new hybrid precoding system that significantly reduces both calculational complexity and energy consumption.The primary idea is to generate several sub-channels with equal gain by dividing the channel by the geometric mean decomposition(GMD).In this process,the objective function of the spectral efficiency is derived,then the basic tracking principle and least square(LS)techniques are deployed to design the proposed hybrid precoding.Simulation results show that the proposed algorithm significantly improves system performance and reduces computational complexity by more than 45%compared to traditional algorithms.

Synthesis,sintering,and thermoelectric properties of the solid solution La_(1–x)Sr_(x)CoO_(3±δ)(0≤x≤1)

In this work, we synthesized cubic perovskite ceramics of the whole La_(1–x)Sr_xCoO_3(0 ≤ x ≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to reach dense ceramics. For x > 0.8, it was necessary to substitute 3% cobalt by silicon to stabilize the cubic perovskite structure. Electrical conductivity increased with Sr content to reach 3×10~5 S·m^(–1) at 330 K for x = 0.3. However, the optimum electrical properties have been found for x = 0.05 at 330 K with PF_(max) = 3.11×10^(–4)W·m^(–1)·K^(–2). Indeed, the Seebeck coefficient was decreasing when x increased to reach values close to 0 for x ≥ 0.3. Thermal conductivity was low at low temperature(≈ 2.5 W×m^(–1)·K^(–1)) and increased up to 6.5 W·m^(–1)·K^(–1) when temperature increased. As the highest power factor was reached at low temperature as well as the lowest thermal conductivity, La_(1–x)Sr_xCoO_3 compounds with low x values appeared as very promising thermoelectric materials around room temperature, on the contrary to layered cobalt oxides. For high x values, Seebeck coefficient values close to zero made these materials unsuitable for thermoelectric applications.

Influence of Bi on the thermoelectric properties of SrTiO_(3-d)

The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in air followed by annealing in a reducing atmosphere.XRD and SEM analyses show that the rutile TiO_(2 i)n Sr_(0.95)TiO_(3) formed after sintering becomes Magn
eli phase of TinO_(2n-1) after annealing.Moreover,Bi resolves from Sr1-xBixTiO_(3 )after annealing,resulting in the formation of Sr1-xBixTiO_(3-δ)/Bi/TinO_(2n-1) composites.With increasing Bi content in Sr1-xBixTiO_(3-δ),the electrical conductivity increases while the absolute values of the Seebeck coefficient decrease as a result of increasing carrier concentration.The thermal conductivity of SrTiO_(3-δ) is reduced by doping Bi up to x=0.07.Highest ZT~0.13 is obtained in Sr0.93Bi0.07TiO_(3-δ) at 1000 K.

On-chip excitation of single germanium vacancies in nanodiamonds embedded in plasmonic waveguides

Monolithic integration of quantum emitters in nanoscale plasmonic circuitry requires low-loss plasmonic configurations capable of confining light well below the diffraction limit.We demonstrated on-chip remote excitation of nanodiamond-embedded single quantum emitters by plasmonic modes of dielectric ridges atop colloidal silver crystals.The nanodiamonds were produced to incorporate single germanium-vacancy(GeV)centres,providing bright,spectrally narrow and stable single-photon sources suitable for highly integrated circuits.Using electron-beam lithography with hydrogen silsesquioxane(HSQ)resist,dielectric-loaded surface plasmon polariton waveguides(DLSPPWs)were fabricated on single crystalline silver plates to contain those of deposited nanodiamonds that are found to feature appropriate single GeV centres.The low-loss plasmonic configuration enabled the 532-nm pump laser light to propagate on-chip in the DLSPPW and reach to an embedded nanodiamond where a single GeV centre was incorporated.The remote GeV emitter was thereby excited and coupled to spatially confined DLSPPW modes with an outstanding figure-of-merit of 180 due to a~six-fold Purcell enhancement,~56%coupling efficiency and~33μm transmission length,thereby opening new avenues for the implementation of nanoscale functional quantum devices.

An Overview on Materials and Techniques in 3D Bioprinting Toward Biomedical Application

Three-dimensional(3D)bioprinting,an additive manufacturing based technique of biomaterials fabrication,is an innovative and auspicious strategy in medical and pharmaceutical fields.The ability of producing regenerative tissues and organs has made this technology a pioneer to the creation of artificial multi-cellular tissues/organs.A broad variety of biomaterials is currently being utilized in 3D bioprinting as well as multiple techniques employed by researchers.In this review,we demonstrate the most common and novel biomaterials in 3D bioprinting technology further with introducing the related techniques that are commonly taking into account by researchers.In addition,an attempt has been accomplished to hand over the most relevant application of 3D bioprinting techniques such as tissue regeneration,cancer investigations,etc.by presenting the most important works.The main aim of this review paper is to emphasis on strengths and limitations of existence biomaterials and 3D bioprinting techniques in order to carry out a comparison through them.

Ba substitution for enhancement of the thermoelectric properties of LaCoO_(3) ceramics(0≤x≤0.75)

In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering. Structural properties of La1-xBaxCoO3 were systematically investigated and thermoelectric properties were measured in the temperature range of 330–1000 K. The results show that the thermoelectric properties of Ba-substituted LaCoO3 depend on x. Indeed, at 330 K, electrical conductivity presents an optimum value for x = 0.25 with a value of σmax ≈ 2.2×105 S·m–1 whereas the Seebeck coefficient decreases when x and/or the temperature increases. The Ba-substituted LaCoO3 samples exhibit p-type semiconducting behaviour. The best power factor value found is 3.4×10–4 W·m–1·K–2 at 330 K for x = 0.075, which is 10% higher than the optimum value measured in La1–xSrxCoO3 for x = 0.05. The thermal diffusivity and thermal conductivity increase with increasing temperature and Ba concentration. La1-xBaxCoO3 shows a maximum figure of merit(ZT = 0.048) for x = 0.05 at 330 K, 25% higher than the best value in La1–xSrxCoO3 compounds.