Application of millimeter-sized polymer cylindrical lens array concentrators in solar cells

A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindrical lens array concentrators are fabricated by the soft imprint technique based on polydimethylsiloxane stamps. The photovoltaic measurements show that millimeter-sized ERP cylindrical lens array concentrators can considerably improve the power conversion efficiency of silicon solar cells. The validity of the proposed method is proved by the coupled optical and electrical simulations. The designed solar cell devices with the advantages of high-efficiency and convenient cleaning are very useful in practical applications.

The forward and inverse problem of cardiac magnetic fields based on concentric ellipsoid torso-heart model

This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source--a current dipole and volume currents. Then by using the simulated magnetic fields based on torso-heart model as input, the cardiac current sources--an array of current dipoles by optimal constrained linear inverse method are constructed. Next, the current dipole array reconstruction considering boundaries is compared with that in an unbounded homogeneous medium. Furthermore, the influence of random noise on reconstruction is also considered and the reconstructing effect is judged by several reconstructing parameters.

A compact and high-power silicon-wafer solar strip-cells-array module integrated with an array concentrator

A compact, low-cost and high-output-power silicon-wafer solar strip-cells-array module （SCAM） wus experimentally demonstrated. The proposed SCAM consisted mainly of a silicon-wafer strip-cell sparse array and low-concentration- ratio array concentrator based on an epoxy resin polymer （ERP） cylindrical piano-convex lens. A polymer replication process based on a polydimethylsiloxane mold was used to fabricate the ERP lens array concentrator. The results show that 46.94% of the silicon-wafer cell was saved in the designed SCAM. Moreover, the output power of the SCAM with a low concentration ratio of 8 suns was improved by 8.6%, compared with a whole piece of a conventional silicon-wafer solar cell with the same area as the module. The proposed method encapsulating solar cells provides a means to reduce the usage of silicon cells in modules as well as improving the output power of modules.

Synthesis and application of TiO_2 single-crystal nanorod arrays grown by multicycle hydrothermal for dye-sensitized solar cells

TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned Tit2 nanorod arrays （NRs） are grown on the fluorine-doped tin oxide （FTO） substrates by a multicycle hydrothermal synthesis process. The samples are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high-resolution transmission electron microscopy （HRTEM）, and selected-area electron diffraction （SAED）. It is found that dye-sensitized solar cells （DSSCs） assembled by the as-prepared Tit2 single-crystal NRs exhibit different trends under the condition of different nucleation and growth concentrations. Optimum cell performance is obtained with high nucleation concentration and low growth cycle concentration. The efficiency enhancement is mainly attributed to the improved specific surface area of the nanorod.

Concentration sensing system with monolithic InGaN/GaN photonic chips

Using an identical monolithic InGaN/GaN light emitting diode (LED) array as the sensing module and a well-designed data processing module, we demonstrate a small-size concentration sensing prototype. Overlap between the emission and the response spectra of the InGaN/GaN LED makes each pair of LEDs in the arrayed chip form a sensing channel. The changes in liquid concentration can be transformed into variation of photocurrent. The system's sensing properties are further optimized by varying the position, number of receivers, and packaging reflectors. With methyl orange as a tracer agent, the sensing system's resolution is 0.286 μmol/L with a linear measurement region below 40 μmol/L.

A Concentric Array for Generating Multimode OAM Waves

For the problem of multiplexing multimodal vortex electromagnetic waves,a double-ring concentric uniform circular array(CUCA)consisting of 12 circularly polarized antennas(4 inner rings and 8 outer rings)is proposed in this paper.A complex feeding network is solved by rotating the circularly polarized antennas at a certain angle.The antennas are rotationally symmetric and point to the center,generating orbital angular momentum(OAM)waves by feeding the same amplitude and phase signals.In addition,this paper combines millimeter wave(mm-wave)and ultra-wideband(UWB)with OAM.The proposed antenna array can generate OAM beams at 30∼40 GHz with l=−1,−2.When l=−1 the relative bandwidth is 25.2% and the gain is 8.03 dBi;when l=−2 the relative bandwidth is 27.7% and the gain is 9.43 dBi.The analysis of simulation results shows that the antenna array has UWB performance,good gain,and a standard spiral phase distribution,which can provide some practical significance for modal multiplexing of mm-wave band OAM.

Spectral and Energy Efficiency of Line-of-Sight OAM-MIMO Communication Systems

Not only high spectral efficiency(SE)but also high energy efficiency(EE)are required for future wireless communication systems.Radio orbital angular momentum(OAM)provides a new perspective of mode multiplexing to improve SE.However,there are few studies on the EE performance of OAM mode multiplexing.In this paper,we investigate the SE and EE of a misaligned uniform concentric circle array(UCCA)-based multi-carrier multimode OAM and multiple-input multiple-output(MCMM-OAM-MIMO)system in the line-ofsight(LoS)channel,in which two transceiver architectures implemented by radio frequency(RF)analog synthesis and baseband digital synthesis are considered.The distance and angle of arrival(AoA)estimation are utilized for channel estimation and signal detection,whose training overhead is much less than that of traditional MIMO systems.Simulation results validate that the UCCA-based MCMM-OAM-MIMO system is superior to conventional MIMOOFDM system in the EE and SE performances.