Typhoon Morakot meteorological analyses

Typhoon Morakot yielded record-breaking precipitation and caused severe disasters in Southern Taiwan in early August 2009. This event revealed the desperate need for extreme rainfall and disaster prediction. The multiscale analysis on circulations demonstrates that Typhoon Morakot not only developed in a monsoon trough, which is a large-scale system in favor of the development of convection systems, it was also involved with complicated features of different scales that included typhoon circulation itself, the circulation of northwestward-propagating 10–30-day oscillation, and the circulation of northward-propagating 40–50-day oscillation. The other remarkable features of Typhoon Morakot are: the asymmetric structure of convection, less damage occurred near the typhoon center than at the fringes, and the record-breaking torrential rain in the mountain areas of south Taiwan induced by the flows on the south fringe of the typhoon. The causes of disastrous precipitation from Typhoon Morakot can be stated as: (1) a large-scale environment in favor of convection development and a plentiful vapor supply provided by strong southwesterly flow, (2) the interaction between topography, typhoon circulation, and large-scale circulation resulting in the heavy rainfall in the mountains of Southern Taiwan, and (3) the weakening of steering flow slowed down Morakot's translation speed before it made landfall and extended the duration of heavy precipitation.     

The permeation resistance of polyethylene, polyethylene/polyamide and polyethylene/modified polyamide blown tubes against unleaded gasoline

The barrier resistance of polyethylene (PE), polyethylene/polyamide (PE/PA) and polyethylene/modified polyamide (PE/MPA) blown tubes against gasoline permeation is reported. The blown tubes prepared from pure PE exhibited much poorer gasoline permeation resistance than PE/PA and PE/MPA blown tubes. About 93% of the filled gasoline permeated out of PE blown tubes in 14 days at 40°C. In contrast, the gasoline permeation resistance of the blown tubes improved significantly by blending MPA (or PA) before tube blowing. PE/MPA blown tubes exhibited significantly better gasoline permeation resistance than PE/PA blown tubes of the same PE contents. The order of gasoline permeation resistance of PE/MPA blown tubes is the same as the order of the barrier resistance of MPA resins against gasoline permeation before blending with PE. In fact, by using proper compositions and carefully controlling the MPA morphology, the gasoline permeation resistance of the PE/MPA blown tubes can reach about 360 times better than that of pure PE blown tubes at 25°C. These interesting phenomena were investigated in terms of the morphology, thermal and rheological properties of the base resins and/or blown tubes of PE/PA and PE/MPA blends.     

Automobile drivers’ willingness to pay for moving violation behaviour—Compared to motorcyclists

A triple-bounded dichotomous choice (TBDC) structure and Spike models are applied to investigate the amount of money Taiwan automobile drivers are willing to pay for five types of moving violations, including local street speeding, expressway and freeway speeding, red light running, right turn on red, and drink-driving. Face-to-face survey was conducted at freeway rest areas by targeting passenger car drivers. The Spike model, superior to other tradition models by capturing excessive zero responses, is applied and the estimated results show that speeders would accept willingness to pay (WTP) of US$37 and US$48,¹ respectively, for local roads and expressways and highways, while red-light runners would accept a WTP of US$44, drivers who turn right on red would accept a lower WTP of US$9, and drunk drivers will accept a WTP as high as US$597. Interestingly, the difference in WTP for drunk driving between drivers and motorcyclists is significant, while others are not.     

Identification of dioxin and dioxin-like polychlorbiphenyls in plant tissues and contaminated soils

The environmental analysis laboratory (EAL) of the Taiwan environmental protection administration (TEPA) has been monitoring certain sites polluted in southern Taiwan by pentachlorophenol manufacture. The analytical results revealed peculiarities in the concentration distributions in plant tissues. There are no available data on dioxin and dioxin-like polychlorbiphenyls (DL-PCBs), which can be taken up from contaminated soils by plant tissues. Thus, the aims of this study were to identify, understand, and to validate these dioxin and DL-PCBs concentrations in plant tissues of the contaminated soils. This research analyzed ten species of plant tissues, including tappa (Boussonetia papyrifera) and common jasmin orange (Murraya paniculata) from sites in southern Taiwan, with different levels of contamination. Dioxin concentrations in these plant tissues ranged from 12.7 to 2919 ng WHO-TEQ(DF)/kg dry weight (d.w.), with average of 463 ng WHO-TEQ(DF)/kg d.w. (n=16). The DL-PCBs concentrations ranged from 0.236 to 1.75 ng WHO-TEQp/kg d.w., with an average of 0.605 ng WHO-TEQp/kg d.w. (n=8). Tappa is one of the most common and fastest growing plants in Taiwan. It also shows the highest tolerance to environmental contaminants and accumulates dioxin and DL-PCBs. This is one of the best species to take up dioxins and DL-PCBs effectively. It can be recommended as a candidate for dioxin and DL-PCB phyto-remediation. These data are useful to evaluate bioaccumulation of dioxin and DL-PCBs, and to study the capability of phyto-remediation in contaminated soils.     

New three-port DC-AC inverter outputting a single-phase and a set of three-phase AC voltages

A conventional DC-AC inverter can only output either a single-phase AC voltage or a set of three-phase AC voltages. A new three-port DC-AC inverter which can simultaneously output a single-phase AC voltage and a set of three-phase AC voltages is proposed in this paper. This three-port DC-AC inverter is based on the three-port T-type multi-level power converter which is composed of three T-type power electronic legs, a decoupling transformer set, a filter inductor set, a single-phase filter capacitor, and a three-phase filter capacitor set. The DC port of the proposed power converter is connected to a DC power source to act as the input port, and the single-phase AC port and the three-phase AC port serve as two output ports to supply power to the single-phase load and the three-phase load, respectively. The zero-sequence transformer is used to decouple the single-phase and three-phase AC components, which are generated by the three T-type power electronic legs. The operation principle of this three-port DC-AC inverter is analyzed, and a hardware prototype is established to verify the performance of the proposed three-port DC-AC inverter. The experimental results are as expected.     

Versatile α,ω‐Disubstituted Tetrathienoacene Semiconductors for High Performance Organic Thin‐Film Transistors

Facile one‐pot [1 + 1 + 2] and [2 + 1 + 1] syntheses of thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene (tetrathienoacene; TTA) semiconductors are described which enable the efficient realization of a new TTA‐based series for organic thin‐film transistors (OTFTs). For the perfluorophenyl end‐functionalized derivative DFP‐TTA , the molecular structure is determined by single‐crystal X‐ray diffraction. This material exhibits n‐channel transport with a mobility as high as 0.30 cm²V^?1s^?1 and a high on‐off ratio of 1.8 × 10⁷. Thus, DFP‐TTA has one of the highest electron mobilities of any fused thiophene semiconductor yet discovered. For the phenyl‐substituted analogue, DP‐TTA , p‐channel transport is observed with a mobility as high as 0.21 cm²V^?1s^?1. For the 2‐benzothiazolyl (BS‐) containing derivative, DBS‐TTA , p‐channel transport is still exhibited with a hole mobility close to 2 × 10^?3 cm²V^?1s^?1. Within this family, carrier mobility magnitudes are strongly dependent on the semiconductor growth conditions and the gate dielectric surface treatment.     

Enhanced output power in an InGaN-GaN multiquantum-welllight-emitting diode with an InGaN current-spreading layer

InGaN-GaN multiple quantum-well (MQW) light-emitting diodes (LEDs) with InGaN current-spreading layer were grown by metal-organic vapor-phase epitaxy (MOVPE) and their characteristics were evaluated by current-voltage (I-V), as well as output power measurements. Experimental results indicate that the LEDs exhibited a higher output power and a lower operation voltage than that of conventional LEDs. The external quantum efficiency of InGaN-GaN MQW LEDs for bare chips operated at injection current of 20 mA with InGaN current spreading layer near 5%. This is two times higher than that of conventional LEDs. This could be tentatively attributed to the better current-spreading effect resulting from Si-doped In_0.18Ga_0.82N wide potential well in which electron states are not quantized     

A dual-beam asymmetrically scanning leaky-wave antenna by utilizinga HEMT resistive upconverter

A dual-beam asymmetrical scanning microstrip leaky-wave antenna (LWA) has been demonstrated in this paper. A HEMT resistive upconverter output is connected to one terminal of the LWA, and a local oscillator (LO) signal is connected to the other terminal. In this experiment, we set the LO frequency at 9.5 GHz so that the right beam is fixed at 48°. By changing the IF frequency from 0.7 GHz to 1.5 GHz, the module of the LWA can steer the left main beam of the far-field pattern from 136° to 158° (the total scanning angle of 22°). Comparisons between the measured and theoretical results indicate that the design can achieve the asymmetrically scanning capability and agree well over the tuning bandwidth of 0.8 GHz