TCM with preswitching diversity in slow Rayleigh fading forwardlink

The performance of trellis-coded modulation with finite interleaver size degrades in a very slow fading channel. In this case antenna diversity is effective. In personal communication systems, however, the limited size and complexity of the handset make diversity implementation at the handset difficult. The authors propose a scheme for obtaining interleaving effects by switching base station antennas in a forward link, without additional software or hardware in a small handset. Computer simulation shows that this scheme has significant performance gain in a slow fading forward link     

The role of antimicrobial peptides in preventing multidrug-resistant bacterial infections and biofilm formation

Over the last decade, decreasing effectiveness of conventional antimicrobial-drugs has caused serious problems due to the rapid emergence of multidrug-resistant pathogens. Furthermore, biofilms, which are microbial communities that cause serious chronic infections and dental plaque, form environments that enhance antimicrobial resistance. As a result, there is a continuous search to overcome or control such problems, which has resulted in antimicrobial peptides being considered as an alternative to conventional drugs. Antimicrobial peptides are ancient host defense effector molecules in living organisms. These peptides have been identified in diverse organisms and synthetically developed by using peptidomimic techniques. This review was conducted to demonstrate the mode of action by which antimicrobial peptides combat multidrug-resistant bacteria and prevent biofilm formation and to introduce clinical uses of these compounds for chronic disease, medical devices, and oral health. In addition, combinations of antimicrobial peptides and conventional drugs were considered due to their synergetic effects and low cost for therapeutic treatment.     

High‐Performance n‐Channel Thin‐Film Field‐Effect Transistors Based on a Nanowire‐Forming Polymer

A new electrontransport polymer, poly{[N,N′‐dioctylperylene‐3,4,9,10‐bis(dicarboximide)‐1,7(6)‐diyl]‐alt‐[(2,5‐bis(2‐ethyl‐hexyl)‐1,4‐phenylene)bis(ethyn‐2,1‐diyl]} (PDIC8‐EB), is synthesized. In chloroform, the polymer undergoes self‐assembly, forming a nanowire suspension. The nanowire's optical and electrochemical properties, morphological structure, and field‐effect transistor (FET) characteristics are investigated. Thin films fabricated from a PDIC8‐EB nanowire suspension are composed of ordered nanowires and ordered and amorphous non‐nanowire phases, whereas films prepared from a homogeneous PDIC8‐EB solution consist of only the ordered and amorphous non‐nanowire phases. X‐ray scattering experiments suggest that in both nanowires and ordered phases, the PDIC8 units are laterally stacked in an edge‐on manner with respect to the film plane, with full interdigitation of the octyl chains, and with the polymer backbones preferentially oriented within the film plane. The ordering and orientations are significantly enhanced through thermal annealing at 200 °C under inert conditions. The polymer film with high degree of structural ordering and strong orientation yields a high electron mobility (0.10 ± 0.05 cm² V^?1 s^?1), with a high on/off ratio (3.7 × 10⁶), a low threshold voltage (8 V), and negligible hysteresis (0.5 V). This study demonstrates that the polymer in the nanowire suspension provides a suitable material for fabricating the active layers of high‐performance n‐channel FET devices via a solution coating process.     

A Two-Step-Recess Process Based on Atomic-Layer Etching for High-Performance $hbox{In}_{0.52}hbox{Al}_{0.48}hbox{As}hbox{/}hbox{In}_{0.53} hbox{Ga}_{0.47}hbox{As}$ p-HEMTs

We investigated 60-nm In_0.52Al_0.48As/In_0.53Ga_0.47As pseudomorphic high-electron mobility transistors (p-HEMTs) fabricated by using a Ne-based atomic-layer-etching (ALET) technology. The ALET process produced a reproducible etch rate of 1.47 Aring/cycle for an InP etch stop layer, an excellent InP etch selectivity of 70 against an In_0.52Al_0.48As barrier layer, and an rms surface-roughness value of 1.37 Aring for the exposed In_0.52Al_0.48As barrier after removing the InP etch stop layer. The application of the ALET technology for the gate recess of 60-nm In_0.52Al_0.48As/In_0.53Ga_0.47As p-HEMTs produced improved device parameters, including transconductance (G_M), cutoff frequencies (f_T)> and electron saturation velocity (vsat) in the channel layer, which is mainly due to the high etch selectivity and low plasma-induced damage to the gate area. The 60-nm In_0.52Al_0.48As/In_0.53Ga_0.47As p-HEMTs fabricated by using the ALET technology exhibited G_M,_Max = 1-17 S/mm, f_T = 398 GHz, and v_sat = 2.5 X 10⁷ cm/s.     

Design and implementation of dual processor block with shared external cache memory

The availability of low cost, high performance microprocessors has led to various designs of shared memory multiprocessor systems. As a result, commercial products which are based on shared memory have been proliferated. Such a multiprocessor system is heavily influenced by the structure of memory system and it is not difficult to find that most configurations include local cache memories. The more processors a system carries, the larger local cache memory is needed to maintain the traffic to and from the shared memory at reasonable level. The implementation of local cache memories, however, is not a simple task because of environmental limitations. In particular, the general lack of board space availability presents a formidable problem. A cache memory system usually needs space mostly to support its complex control logic circuits for the cache itself and network interfaces like snooping logic circuits for shared bus. Although packaging can be made denser to reduce system size, there are still multiple processors per board. It requires a more area-efficient cache memory architecture. This paper presents a design of shared cache for dual processor board of bus-based symmetric multiprocessors. The design and implementation issues are described first and then the evaluation and measurement results are discussed. The shared cache proposed in this paper has been determined to be quite area-efficient without the significant loss of throughput and scalability. It has been implemented as a plug-in unit for TICOM, a prevalent commercial multiprocessor system.     

Predispersed solvent extraction of negatively complexed copper from water using colloidal liquid aphron containing a quaternary ammonium salt

Negatively complexed copper ion by complexing agent like EDTA (Ethylenediaminetetraacteic acid) was removed by predispered solvent extraction (PDSE) using colloidal liquid aphrons (CLAs) made out of Trioctylmetylammonium chloride (Aliquat 336) diluted with nonpolar kerosene. PDSE was found to have higher mass transfer rate than conventional solvent extraction under experimental conditions without mechanical mixing. The effect of type of water-soluble surfactants, phase volume ratio (PVR), concentration of anionic Sodium Dodecyl Benzene Sulfonate (SDBS) on PDSE was investigated. In addition, the effect of anionic SDBS on back extraction in PDSE was also studied. Under experimental conditions with enough mechanical mixing, the amount of copper transferred to Aliquat 336 core from the pregnant phase was compared in both PDSE by using anionic SDBS and conventional solvent extraction. It is concluded that PDSE using Aliquat 336 CLA can be used for treatment of negatively complexed copper without the influence of surfactant. To optimize CLAs-based process, stability of CLAs containing a quaternary ammonium salt Aliquat 336 diluted with kerosene in the continuous phase was investigated by measuring the volume released to surface. To destabilize CLAs, H⁺, OIL were added. Stability of CLAs was estimated by comparing the half-life obtained. Break-up of destabilization follows pseudo-first-order reaction kinetics at low ionic strength. But, pseudo-first-order model cannot be applied to a region of high ionic strength.     

Design of Middleware for Interactive Data Services in the Terrestrial DMB

In this letter, we introduce a new middleware architecture and its generic application programming interface (API) (called the T‐DMB MATE API) for terrestrial digital multimedia broadcasting (T‐DMB). Middleware in T‐DMB enables inter‐operable applications to be downloaded from both broadcast and telecommunication networks in advance and to be executed in any type of T‐DMB receiver. The middleware we introduce here is especially designed to support a proposed method for application provisions applied to a concept of application module appropriate to the service environment of T‐DMB. We also verify the designed T‐DMB MATE API through the implementation of the middleware and its application in a PC‐based receiver.     

Assessment of a DNB-type theoretical critical heat flux model for rod bundles with non-uniform axial power shapes

A general critical heat flux (CHF) prediction method with a wide applicable range and reasonable accuracy is essential to the thermal-hydraulic design and safety analysis at the conceptual design stage for a new pressurized water reactor (PWR). In this study, the Korea Advanced Institute of Science and Technology (KAIST) liquid sub-layer dryout CHF prediction model for Departure from Nucleate Boiling (DNB) region has been implemented in a sub-channel analysis code, and investigated for the method's possible use in a rod bundle environment with various non-uniform axial power shapes. The KAIST model showed comparable prediction capability to Lin's method for bottom-, center-, and top-peaked heat flux shapes. The KAIST model, without any correction factors or empirical constants, turned out to be suitable to fulfill the needs for a basis of a general CHF prediction method as compared to Lin's method and Westinghouse-3 (W-3) correlation.     

Photo‐ and Rubbing‐Alignable Brush Polyimides Bearing Three Different Chromophores

Three new photoreactive brush polyimides (PSPIs), each bearing a different type of chromophore (cinnamoyl (CA), 3‐(2‐furyl)acryloyl (FA), and methacryloyl (MA)) in their bristles (i.e., side groups), are successfully synthesized, and are found to produce good‐quality films with smooth surfaces through conventional spin‐casting and drying processes. These PSPI polymers are thermally stable up to 320 °C. This is the first quantitative investigation of the photoaligning and rubbing‐aligning processabilities of PSPI polymer films, and of the abilities of the resultant films to control the orientation and anchoring of liquid‐crystal (LC) molecules. The chromophores of both poly(1‐cinnamoyloxy‐2,4‐phenylene hexafluoroisopropylidenediphthalimide) (6F‐DAP‐CA) and poly(1‐3‐(2‐furyl)acryloyloxy‐2,4‐phenylene hexafluoroisopropylidenediphthalimide) (6F‐DAP‐FA) PSPIs are found to undergo photodimerization in thin films and, to a lesser extent, photoisomerization, resulting in insoluble, crosslinked films. The MA chromophores of 6F‐DAP‐MA PSPI are found to undergo photopolymerization in thin films, which might include photodimerization to a lesser extent, resulting in insoluble, crosslinked films. Thin films of the PSPI polymer chains are found to have excellent unidirectional orientation ability as a result of either photoexposure with linearly polarized UV light (LPUVL) or rubbing. Both the photoaligned and the rubbing‐aligned polymer chains in the PSPI films are demonstrated to effectively induce the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The contribution to LC alignment of the microgrooves developed in the rubbed films is found to be very low. The anchoring energies of the LCs on the photoaligned film surfaces are comparable to those on the rubbing‐aligned film surfaces; the anchoring energies are found to be in the range 0.45–2.25 × 10^–5 J m^–2, and to depend on which film treatment process is used and which chromophore bristle is present. In summary, the new PSPIs reported in this paper are promising LC alignment‐layer candidates with rubbing‐free processing for the production of advanced LC‐display (LCD) devices, including LCD televisions with large display areas.     

Evaluation offing surfaces with several coatings for friction, wear and scuffing life

Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission. Many engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating period. Therefore, it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel engine. Wear and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear tester. The tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed pin. Several coatings on the ring specimen were used, such as DLC, TiN, Cr-ceramic and TiAlN, in order to improve the tribological characteristics of the ring. The coefficients of friction were monitored during the tests, and the wear volumes of the piston ring surfaces with various coatings were compared. Test results show that the DLC coating exhibits better tribological properties than the other coatings. The graphite structure of this coating is responsible for the low friction and wear of the DLC film. The TiN and DLC coatings show better scuffing resistance than the other coatings. The TiN and Cr-ceramic coated rings show good wear resistance and high friction.