An Approach for Segmentation of Airborne Laser Point Clouds Utilizing Scan‐Line Characteristics

In this study, we suggest a new segmentation algorithm for processing airborne laser point cloud data which is more memory efficient and faster than previous approaches. The main principle is the reading of data points along a scan line and their direct classification into homogeneous groups as a single process. The results of our experiments demonstrate that the algorithm runs faster and is more memory efficient than previous approaches. Moreover, the segmentation accuracy is generally acceptable.     

The analysis and compensation of dead-time effects in PWM inverters

The quantitative prediction of the dead-time effect in pulse width modulated (PWM) inverters is addressed. Through analysis and simulation it is shown that the effect results in a decrease of the fundamental component and an increase in the low-order harmonics in the output voltage of the inverter. To compensate the effect, two simple methods, which are adequate for sinusoidal PWM and memory-based PWM, respectively, are presented. Experimental results show the validity of the analysis and the usefulness of the compensation methods     

Effects of Interfacial Dielectric Layers on the Electrical Performance of Top‐Gate In‐Ga‐Zn‐Oxide Thin‐Film Transistors

We investigate the effects of interfacial dielectric layers (IDLs) on the electrical properties of top‐gate In‐Ga‐Zn‐oxide (IGZO) thin film transistors (TFTs) fabricated at low temperatures below 200°C, using a target composition of In:Ga:Zn = 2:1:2 (atomic ratio). Using four types of TFT structures combined with such dielectric materials as Si₃N₄ and Al₂O₃, the electrical properties are analyzed. After post‐annealing at 200°C for 1 hour in an O₂ ambient, the sub‐threshold swing is improved in all TFT types, which indicates a reduction of the interfacial trap sites. During negative‐bias stress tests on TFTs with a Si3N4 IDL, the degradation sources are closely related to unstable bond states, such as Si‐based broken bonds and hydrogen‐based bonds. From constant‐current stress tests of Id = 3 µA, an IGZO‐TFT with heat‐treated Si₃N₄ IDL shows a good stability performance, which is attributed to the compensation effect of the original charge‐injection and electron‐trapping behavior.     

Analysis of adjacent channel interference using distribution function for V2X communication systems in the 5.9‐GHz band for ITS

Many use cases have been presented on providing convenience and safety for vehicles employing wireless access in vehicular environments and long‐term evolution communication technologies. As the 70‐MHz bandwidth in the 5.9‐GHz band is allocated as an intelligent transportation system (ITS) service, there exists the issue that vehicular communication systems should not interfere with each other during their usage. Numerous studies have been conducted on adjacent interfering channels, but there is insufficient research on vehicular communication systems in the ITS band. In this paper, we analyze the interference channel performance between communication systems using distribution functions. Two types of scenarios comprising adjacent channel interference are defined. In each scenario, a combination of an aggressor and victim network is categorized into four test cases. The minimum requirements and conditions to meet a 10% packet error rate are analyzed in terms of outage probability, packet error rate, and throughput for different transmission rates. This paper presents an adjacent channel interference ratio and communication coverage to obtain a satisfactory performance.     

Shorted Microstrip Patch Antenna Using Inductively Coupled Feed for UHF RFID Tag

A very small patch‐type RFID tag antenna (UHF band) using ceramic material mountable on metallic surfaces is presented. The size of the proposed tag is 25 mm×25 mm×3 mm. The impedance of the antenna can be easily matched to the tag chip impedance by adjusting the size of the shorting plate of the patch and the size of the feeding loop. The measured maximum reading distance of the tag at 910 MHz was 5 m when it was mounted on a 400 mm × 400 mm metallic surface. The proposed design is verified by simulation and measurements which show good agreement.     

Writing current reduction and total set resistance analysis in PRAM

We evaluated the limit of scaling bottom electrode contact (BEC) heater size and high resistivity heater to reduce writing current. It was found that the resistivity of heater should be increased for reducing writing current below the heater size of about 50 nm without any undesirable increase of resistance of the crystalline state (SET state, Rset). It was shown in the numerical simulations that the dissipated heat loss through BEC during melting GST was decreased in the increase of resistivity of heater. In addition, we analyzed the resistance components contributing to the total set resistance. It was observed that the undesired sharp increase of Rset as the BEC size decreases below 50 nm was attributed to the resistance component of GST–BEC interface. In the case of high resistivity heater, the contributions of both incomplete crystallization and heater itself were enhanced.     

Complementary integrated circuits on plastic foil using inkjet printed n- and p-type organic semiconductors: Fabrication,characterization, and circuit analysis

Complementary thin-film transistor circuits composed of 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS–PEN) and a rylene carboxylic diimide derivative for p- and n-channel thin-film transistors (TFTs) were fabricated on flexible foils. The so-called staggered TFT configuration is used, meaning that the semiconductors layers are deposited last. The work-function of the injecting gold electrodes were modified using several self-assembled monolayers (SAMs). For optimized contacts the mobility of the n- and p-channel TFTs was 0.5 cm²/Vs and 0.2 cm²/Vs, respectively. Strongly degraded performance is obtained when the n-channel material was printed on contacts optimized for the p-channel TFT, and vice versa. This illustrates that for CMOS circuits we need careful work-function engineering to allow proper injection for both electrons and holes. We show for the first time that by using a bimolecular mixture for the SAM we can systematically vary the work function, and demonstrate how this affects the performance of discrete n-type and p-type transistors, as well as CMOS inverters and ring oscillators. Under optimal processing conditions we realized complementary 19-stage ring oscillators with 10 μs stage delay operating at 20 V.     

Determination of the interface energy level alignment of a doped organic hetero-junction using capacitance–voltage measurements

A simple method based on capacitance–voltage (C–V) measurements is reported to determine the interface energy level alignment at the junction of 15 mol% Cs₂CO₃ doped 4,7-diphenyl-1,10-phenanthroline (BPhen) and 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN) fabricated under high vacuum. The junction properties, such as the depletion layer thickness, built-in potentials and vacuum level shift were calculated with simple Mott–Schottky and Poisson’s equations with the boundary condition of a continuous electric flux density using the information from the C–V data. The interface energy level alignment determined by this method is well matched with the one determined using the in situ ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS) experiments performed under ultra-high vacuum. This method can be applied to other semiconductor junctions such as the organic p–n homojunctions and heterojunctions with known energy levels, as long as the metal/semiconductor contact is Ohmic without referring to the photoemission spectroscopies. Moreover, the energy level alignment determined by the C–V measurement gives a more realistic result since the films for the measurements are formed under high vacuum which is a normal device fabrication environment rather than under ultra high vacuum.     

Octupolar Films with Large Second Harmonic Generation and Electro‐Optical Effects

Thin films that benefit from efficient octupolar molecular packing are prepared for second harmonic generation (SHG) and electro‐optic (EO) applications. The films are composed of 1,3,5‐tricyano‐2, 4,6‐tris(p‐diethylaminostyryl)benzene (TTB) in a ploymethylmetacrylate (PMMA) matrix on aluminum/BK7 glass (Al/BK7) and polyimide/indium tin oxide (PI/ITO) substrates. Octupolar films prepared on both substrates display polycrystalline and cylindrical domains. The molecular orientation, SHG efficiencies, and EO coefficients of the crystalline domains are measured. In the cylinders, the molecular crystal planes are oriented perpendicularly to the major cylinder axis, whereas in the polycrystals, the planes are randomly oriented. While both structures exhibit high and stable SHG and EO efficiencies, the cylinders, in particular, exhibited a very large SHG, a large EO coefficient, and high thermal stability; these characteristics will be useful in second order nonlinear optical applications.     

Performance analysis and simulation of OCDMA system based on FBGs encoder/decoder

The encoding/decoding scheme based on Fiber Bragg Grating （FBG） for Optical Code Division Multiple Access （OCDMA） system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate （BER） of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio （SIR） and BER performance of the system are studied and simulated at the case with uneven distribution of chips＇ powers.