On the profile of frequency and voltage dependent interface states and series resistance in (Ni/Au)/Al0.22Ga0.78N/AlN/GaN heterostructures by using current–voltage (I–V) and admittance spectroscopy methods

Cataloged from PDF version of article.In order to explain the experimental effect of interface states (N-ss) and series resistance (R-s) of device on the non-ideal electrical characteristics, current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics of (Ni/Au)/Al0.22Ga0.78N/AlN/GaN heterostructures were investigated at room temperature. Admittance measurements (C-V and G/omega-V) were carried out in frequency and bias voltage ranges of 2 kHz-2 MHz and (-5 V)-(+5 V), respectively. The voltage dependent R-s profile was determined from the I-V data. The increasing capacitance behavior with the decreasing frequency at low frequencies is a proof of the presence of interface states at metal/semiconductor (M/S) interface. At various bias voltages, the ac electrical conductivity (sigma(ac)) is independent from frequencies up to 100 kHz, and above this frequency value it increases with the increasing frequency for each bias voltage. In addition, the high-frequency capacitance (C-m) and conductance (G(m)/omega) values measured under forward and reverse bias were corrected to minimize the effects of series resistance. The results indicate that the interfacial polarization can more easily occur at low frequencies. The distribution of N-ss and R-s is confirmed to have significant effect on non-ideal I-V. C-V and G/omega-V characteristics of (Ni/Au)/Al0.22Ga038N/AlN/GaN heterostructures. (C) 2011 Elsevier Ltd. All rights reserved

DEVELOPING A MODEL FOR TEACHING THE PROBLEMATIC VOCABULARY ITEMS BY COMPUTER

This study proposes a new design of computer-based vocabulary teaching learning and teaching activity so as to enhance opportunities for learners to expand their vocabulary knowledge. There are a lot of opportunities on the internet to compensate the hampering effect of learning vocabulary items and to improve their vocabulary by means pronunciation, intonation, meaning of target language vocabulary items by using internet facilities with almost no expenses. In this research, a new vocabulary teaching model, called Morphological Pairing Model,is proposed by using electronic dictionaries, audacity programs, and text to speech labs. Some vocabulary items are really difficult to learn due to the shift of stress phonemes, internal vowel changes, intonation, and meaning variation. In this model, problem-causing words are diagnosed and then collected via diagnostic tests. Then, words are grouped in terms of morphological pairs regarding the psycholinguistic difficulties they inherit. Later, the pronunciation and transcription of them are put together in isolation for repetition by downloading them from the electronic dictionaries. Finally, some sentences for each vocabulary item are written down, and while the speaking robots from the Text to Speech Labsread them out, they are downloaded by the Audacity programs. After this, the foreign language teacher designs different types of exercises and practices them in native speaker-like pronunciation and intonation in form of a PowerPoint, which is handed over to the students at the end of the lesson after the classroom practices are over for further practice on their own.                                                                                                                                      

The Phonological Structures of Open and Close Junctures in Utterances for English Teachers

Junctures are specific phonemes in English language and work like what the traffic lights do in the structures of phrases at the beginning, in the middle, and at the end of the words, phrases, clauses, and sentences. They indicate both the pauses and continuation in the flow of speech in between or among the utterances some of which can be the cause of misperceptions and misunderstandings. At the word and phrase level, open and close junctures come to the stage to give hard times to the non-native speakers in perception of speech and production of speech. By nature, sounds signal pauses, segmentation, and which the listeners need them to perceive the spoken utterances. Close junctures take place in compound words while the open or plus junctures are situated in or among the phrases. They both change the meanings of utterances; therefore, they are accepted as phonemes in English. If they are not perceived by the listeners, they change the meanings of utterances and thus the listeners are misled and soon find themselves in communication breakdown. Key words: juncture phoneme, pause, open juncture, close junctur

An Information Theory Based Representation of Software Systems and Design

Software designers can benefit from the experience of engineering designers and information theory formalism. Every design starts with uncertainty and the art of software design involves uncertainty reduction. Information theory enables software designers to adopt a systems view that facilitates intellectual control over a given software design. Since design imposes organization through successive transformations in reaching the final product, it is possible to formalize design with information theory. We investigated software design as a hierarchical decomposition of design spaces. We realized that before initiating the software design process there is minimal organization, representing higher entropy. The design decisions carrying out design activities through hierarchical decomposition reduce uncertainty and therefore introduce comparatively higher organization represented by lower entropy. In this dissertation, the communication channel representation of software is developed through a process of 1) set-theoretical representation, 2) mapping to a communication channel formalism and 3) hierarchical decomposition leading to entropy reduction. This information theoretical representation allows investigating the properties of software systems as communication channels

Long vowels versus diphthongs in North American English: Which one is easy to recognize and hear?

The aim of this presentation is to measure to what extent long vowels are confused with diphthongs by Turkish English majors. A diphthong is made of two components. By definition and sound structure, diphthongs are a combination of two separate vowel sounds that, when uttered, the first vowel glides onto the second vowel forming a single syllable, as heard in /aɪ, aʊ, eɪ, oʊ, ɔɪ/. By nature, diphthongs happen to be long vowels. Long vowels, on the other hand, do not include two vowels that do not glide, as in /ɑ:, i:, u:, ju:, ɔ:, ɜ:/. No vowel sound has a fixed length and many other factors affect length, such as the voiced consonant sound directly after a vowel sound will affect its length (voicing), reduction and intonation. It is said that to hear vowel sounds within words is easier than it is to hear the sound alone. Long vowels are generally said to be the easiest vowels for non-native English speakers to distinguish and hear correctly. This assumption will be tested with 30 instructors of English language education who are enrolled for MA degree at a foundation university in Ankara. The perception of long vowels vs diphthongs in written words and the audition of them in oral forms were measured within two separate applications of a pre-test and a post-test. It was discovered that the Turkish English instructors perceived the diphthongs (86, 3%) better than long vowels (73,3% ). It was deduced that the main cause of learning difficulty behind the diphthongs and long vowels, apart from L1 intervention, was the fact that Turkish learners of English suffer from a psycho-orthographic trauma created by the spelling of the diphthongs and long vowels by means of several letters

Comparison of the impacts of different multimodalities on incidental L2 vocabulary learning

Multimodality of input in incidental L2 vocabulary learning has recently been a topic of interest among language acquisition researchers, yet the results have been somewhat contradictory. This study seeks to compare the impacts of two different multimodalities on incidental L2 vocabulary learning, namely, reading-plus-watching (experimental group I) vs. reading-plus-listening (experimental group II), as compared to the reading only condition, which is included as a control measure. Experimental group I watched and read the transcriptions of four news texts with electronic glosses for the target words, while experimental group II read and listened to the same news texts again with electronic glosses for the same 20 target words. Next, the two experimental groups swapped roles with a new set of four news texts glossed for another group of 20 target words. The control group only read the same eight news texts without glosses. The results suggest that reading-plus-listening can be a more conducive multimodal presentation for incidental vocabulary learning as compared to reading-plus-watching. The results also challenge the validity of some principles of the Cognitive Theory of Multimedia Learning in incidental L2 vocabulary learning, while providing supporting evidence for some other principles