Phone Models Research Articles

Estimating Manual Test Execution Effort and Capacity Based On Execution Points

In some domains, such as the mobile application domain, functional tests may not be feasible to automate due to limited test automation technology (multimedia support, etc.) or high cost to port automated tests for different phone models and operating systems. In this context, test teams should be able to estimate the effort required to manually execute tests on schedule.Although several effort estimation approaches have been proposed over the years, none of them are appropriate for estimating manual test execution effort. The main reason for that is the lack of size measures for test projects. In this paper, we present execution points, a measure for the size and execution complexity of tests that is calculated based on test specifications. We also show how to estimate manual test execution effort and capacity based on this measure. Finally, results from an empirical study suggested the viability of our proposed measure.

DESIGN ANALYSIS OF FERRITE SHEET ATTACHMENT FOR SAR REDUCTION IN HUMAN HEAD

In this paper, reducing Speciflc Absorption Rate (SAR) with ferrite sheet attachment is investigated. The flnite-difierence time-domain method with Lossy-Drude model is adopted in this study. The methodology of SAR reduction is addressed and then the efiects of attaching location, distance, size and material properties of ferrite sheet on the SAR reduction are investigated. Computational results show that the SAR averaging over 10gm was better than that for 1gm and SAR reduction of 57.75% is achieved for SAR 10gm. These results show the way to choose a ferrite sheet with the maximum SAR reducing efiect for phone model.

MULTIBAND FRACTAL PLANAR INVERTED F ANTENNA (F-PIFA) FOR MOBILE PHONE APPLICATION

The design of a novel Fractal planar inverted F antenna (F-PIFA) based on the self affinity property is presented in this paper. The procedure for designing a Fractal Planar Inverted F Antenna is explained and three different iterations are designed for use in cellular phones. The F-PIFA has a total dimension of 27 mm × 27 mm and has been optimized to be operational at GSM (Global System for Mobile Communication), UMTS (Universal Mobile Telecommunication System) and HiperLAN (High Performance Radio LAN) with the frequencies range from 1900 MHz to 2100 MHz, 1885 to 2200 MHz and 4800 MHz to 5800 MHz respectively. The antenna achieved −6 dB return loss at the required GSM, UMTS and HiperLan frequencies with and has almost omnidirectional radiation pattern. This antenna has been tested using realistic mobile phone model and has met the performance criteria for a mobile phone application. Simple semi-empirical formulas of the operational frequency, numerical calculation and computational SAR of the antenna also has been presented and discussed.

Modelling pronunciation variation with single-path and multi-path syllable models: Issues to consider

In this paper, we construct context-independent single-path and multi-path syllable models aimed at improved pronunciation variation modelling. We use phonetic transcriptions to define the topologies of the syllable models and to initialise the model parameters, and the Baum–Welch algorithm for the re-estimation of the model parameters. We hypothesise that the richer topology of multi-path syllable models would be better at accounting for pronunciation variation than context-dependent phone models that can only account for the effects of the left and right neighbours, or single-path syllable models whose power of modelling segmental variation would seem to be limited. However, both context-dependent phone models and single-path syllable models outperform multi-path syllable models on a large-vocabulary continuous speech recognition task. Careful analyses of the errors made by the recognisers with single-path and multi-path syllable models show that the most important factors affecting the speech recognition performance are syllable context and lexical confusability. In addition, the speech recognition results suggest that the benefits of the greater acoustic modelling accuracy of the multi-path syllable models can only be reaped if the information about the syllable-level pronunciation variation can be linked with the word-level information in the language model.

Phone Theft Index

This study presents what we believe to be the first Phone Theft Index, ranking the most stolen makes and models of mobile cell phones. It is based on over 200,000 recorded crimes involving such theft during 2004 and 2005. The theft “careers” of key phone models are examined. The market for mobile cell phones changes rapidly, as shown in theft career trajectories. The next steps in the development of the index would be for it to be risk-based, and routinely publicized on a timely and frequent basis. Complementary publications of information on “safe” handsets and practices would also stimulate the market in consumer safety.

Distribution of RF energy emitted by mobile phones in anatomical structures of the brain

The rapid worldwide increase in mobile phone use in the last decade has generated considerable interest in possible carcinogenic effects of radio frequency (RF). Because exposure to RF from phones is localized, if a risk exists it is likely to be greatest for tumours in regions with greatest energy absorption. The objective of the current paper was to characterize the spatial distribution of RF energy in the brain, using results of measurements made in two laboratories on 110 phones used in Europe or Japan. Most (97–99% depending on frequency) appears to be absorbed in the brain hemisphere on the side where the phone is used, mainly (50–60%) in the temporal lobe. The average relative SARSAR is the specific energy absorption rate i.e. energy absorption rate per unit mass (measured in W kg−1). is highest in the temporal lobe (6–15%, depending on frequency, of the spatial peak SAR in the most exposed region of the brain) and the cerebellum (2–10%) and decreases very rapidly with increasing depth, particularly at higher frequencies. The SAR distribution appears to be fairly similar across phone models, between older and newer phones and between phones with different antenna types and positions. Analyses of risk by location of tumour are therefore important for the interpretation of results of studies of brain tumours in relation to mobile phone use.

Prediction of Temperature Increase in Human Eyes Due to RF Sources

A numerical study is proposed to investigate the effects of different RF sources on the specific absorption rate (SAR) and maximum temperature increase in the human eye at different frequencies. In particular, a new model of the human head is presented and compared with an anatomical model of the visible human. The high resolution (0.5 mm) of the proposed model allows to consider more eye tissues than previous studies distinguishing the sclera from the retina and choroid. New values of blood perfusion and metabolic rate of these tissues are derived. A plane-wave field is considered as far-field exposure, while realistic models of mobile phone and dipole antennas are used as primary sources for near-field exposure. The obtained results show that the distributions of the SAR and temperature increase depend on the frequency, position, and kind of sources. Finally, attention is paid to the maximum temperature increase in the lens for the SAR values prescribed by the Commission on Non-Ionizing Radiation Protection. To this aim, a scaling approach is proposed, and significant values of temperature increase are found (about C for general public exposure and about 1.5 degC for occupational exposure) for the most critical cases of near-field exposures.

Generation of Phonetic Units for Mixed-Language Speech Recognition Based on Acoustic and Contextual Analysis

This work presents a novel approach to generating phonetic units in order to recognize mixed-language or multilingual speech. Acoustic and contextual analysis is performed to characterize multilingual phonetic units for phone set creation. Acoustic likelihood is utilized for similarity estimation of phone models. The hyperspace analog to language (HAL) model is adopted for contextual modeling and contextual similarity estimation. A confusion matrix combining acoustic and contextual similarities between every two phonetic units is built for phonetic unit clustering. Multidimensional scaling (MDS) method is applied to the confusion matrix for reducing dimensionality. Experimental results indicate that the created phonetic set provides a compact and robust set that considers acoustic and contextual information for mixed-language or multilingual speech recognition.

Morpheme-Based Modeling of Pronunciation Variation for Large Vocabulary Continuous Speech Recognition in Korean

This paper describes a morpheme-based pronunciation model that is especially useful to develop the pronunciation lexicon for Large Vocabulary Continuous Speech Recognition (LVCSR) in Korean. To address pronunciation variation in Korean, we analyze phonological rules based on phonemic contexts together with morphological category and morpheme boundary information. Since the same phoneme sequences can be pronounced in different ways at across morpheme boundary, incorporating morphological environment is required to manipulate pronunciation variation modeling. We implement a rule-based pronunciation variants generator to produce a pronunciation lexicon with context-dependent multiple variants. At the lexical level, we apply an explicit modeling of pronunciation variation to add pronunciation variants at across morphemes as well as within morpheme into the pronunciation lexicon. At the acoustic level, we train the phone models with re-labeled transcriptions through forced alignment using context-dependent pronunciation lexicon. The proposed pronunciation lexicon offers the potential benefit for both training and decoding of a LVCSR system. Subsequently, we perform the speech recognition experiment on read speech task with 34K-morpheme vocabulary. Experiment confirms that improved performance is achieved by pronunciation variation modeling based on morpho-phonological analysis.

이동전화 한글 입력 방식 평가 방법에 관한 문헌 조사

The purpose of this study is to compare assessment techniques for Korean characters entry methods of mobile phones. This study was performed based on survey of relevant existing studies. The assessment techniques were classified into three: 1) predicting entry time using conceptual models such as Fitts' law, Hick-Hyman's law and KLM-GOMS model (conceptual model); 2) counting the number of pressing button(number of pressing button); and 3) measuring performance or rating subjective measures using real mobile phones(real mobile phone). The comparison revealed that the assessment results were different depending upon the techniques used. The results from the conceptual model using only Fitts' law and the number of pressing button were opposite to those from techniques of the real mobile phone and conceptual model using Fitts' and Hick-Hyman's laws. Based on this result and suggestions provided by the literature, it is recommended that for more precisely assessing interfaces of mobile phones such as Korean characters entry method, real mobile phones be used instead of the conceptual models.

Study on SARs in Head Models With Different Shapes by Age Using SAM Model for Mobile Phone Exposure at 835 MHz

Four head models with the outer shapes of different ages were established using the specific anthropomorphic mannequin (SAM) model of IEEE Standard 1528. The criteria of head height, face length, head length, and head breadth by age were applied to build the models. We assumed that the shells of all the head models have the same dielectric properties with the head-equivalent tissue in order to simulate a real pressed ear. The cheek and tilt positions of three bar-type phone models were used, and the positioning processes against each head model were described in detail. Antenna input impedances of the phones under the test positions and specific absorption rate (SAR) distributions in the head models were computed using the finite-difference time-domain (FDTD) technique. Spatial peak SARs averaging over 1 and 10 g were compared for fixed input and radiated powers of all the phones. The effect of the dielectric properties in a younger head model on SAR result was analyzed. First, input resistance of the phone antennas in the cheek position gradually increased when head size grew with age, but those for the tilt position showed a slight decrease. Second, for a fixed input power, the head models by age changed peak 1- and 10-g SARs by approximately 15%. The electromagnetic absorption depths in the head models in the same test position were about the same, but the head-averaged SAR was higher in the younger model because of the smaller head volume. Third, for a fixed radiated power, the peak SARs got relatively lower in the smaller head model and higher in the larger head model, compared with those for the fixed input power since the smaller head model needs lower input power. Fourth, it was shown that simultaneous change in the conductivity and permittivity of head tissue within 20%-30% did not have a significant influence on energy absorption.

Discriminative speaker adaptation using articulatory features

This paper presents an automatic speech recognition system using acoustic models based on both sub-phonetic units and broad, phonological features such as voiced and round as output densities in a hidden Markov model framework. The aim of this work is to improve speech recognition performance particularly on conversational speech by using units other than phones as a basis for discrimination between words. We explore the idea that phones are more of a short-hand notation for a bundle of phonological features, which can also be used directly to distinguish competing word hypotheses. Acoustic models for different features are integrated with phone models using a multi-stream approach and log-linear interpolation. This paper presents a new lattice based discriminative training algorithm using the maximum mutual information criterion to train stream weights. This algorithm allows us to automatically learn stream weights from training or adaptation data and can also be applied to other tasks. Decoding experiments conducted in comparison to a non-feature baseline system on the large vocabulary English Spontaneous Scheduling Task show reductions in word error rate of about 20% for discriminative model adaptation based on articulatory features, slightly outperforming other adaptation algorithms.

Modernity and the Mobile Phone

Modernity and the Mobile Phone

Pronunciation error detection for computer-assisted language learning system based on error rule clustering using a decision tree

Faculty of Engineering, Tohoku University,Aramaki aza Aoba 6–6–5, Sendai, 980–8579 Japan(Received 28 August 2006, Accepted for publication 27 October 2006)Keywords: CALL system, Pronunciation error detection, Decision tree, ClusteringPACS number: 43.72.Ne [doi:10.1250/ast.28.131]1. IntroductionRecently, several computer-assisted language learning(CALL) systems that exploit spoken language technologyhave been developed. Automatic assessment of a learner’spronunciation is one of the main issues of such systems [1].We are developing a mispronunciation detection systembased on multilingual phone models [2]. This method firstprepares ‘mispronunciation rules,’ which are the mispronun-ciations a learner tends to make. When a learner utters asentence presented by the system, the system prepares anacoustic model of the correct pronunciation of the sentenceas well as that of the mispronounced sentence. Then, thelikelihood values of both models are calculated using thelearner’s utterance, and the two likelihood values arecompared with each other. If the likelihood of the correctmodel is higher, the learner’s utterance is likely to be correct.Otherwise, the utterance is concluded to be mispronounced.One problem of the mispronunciation detection method isthat the method tends to evaluate the utterance more strictlythan human evaluators, because the strictness of a humanevaluator depends on the linguistic context of the phoneme tobe evaluated. To solve this problem, the strictness of detectionof a mispronunciation has to be adjusted so that the system’sjudgment becomes similar to that by a human.In this paper, we propose a method of solving thisproblem by adjusting the thresholds of error detection. Thismethod forms several clusters of mispronunciation rules usinga decision tree [3], and the optimum threshold is determinedfor each cluster.2. Pronunciation error detection based on themispronunciation rulesFirst, we explain the framework of the pronunciation errordetection based on multilingual phone models. In this work,the target language is English and the native language of thelearners is Japanese. First, the system gives the learner a wordor a sentence to pronounce. When the learner utters the wordor sentence, the system records the speech and performs anacoustic analysis. Here, the input speech is denoted by O.Next, the system prepares a model of the correct pronunci-ation of the presented word or sentence. The ‘model’ iscomposed of connected hidden Markov models (HMMs),each of which models a phoneme. This model of the correctpronunciation is denoted by . Then, the mispronunciationrules are applied to the correct model to generate the models

A Vector Space Modeling Approach to Spoken Language Identification

We propose a novel approach to automatic spoken language identification (LID) based on vector space modeling (VSM). It is assumed that the overall sound characteristics of all spoken languages can be covered by a universal collection of acoustic units, which can be characterized by the acoustic segment models (ASMs). A spoken utterance is then decoded into a sequence of ASM units. The ASM framework furthers the idea of language-independent phone models for LID by introducing an unsupervised learning procedure to circumvent the need for phonetic transcription. Analogous to representing a text document as a term vector, we convert a spoken utterance into a feature vector with its attributes representing the co-occurrence statistics of the acoustic units. As such, we can build a vector space classifier for LID. The proposed VSM approach leads to a discriminative classifier backend, which is demonstrated to give superior performance over likelihood-based n-gram language modeling (LM) backend for long utterances. We evaluated the proposed VSM framework on 1996 and 2003 NIST Language Recognition Evaluation (LRE) databases, achieving an equal error rate (EER) of 2.75% and 4.02% in the 1996 and 2003 LRE 30-s tasks, respectively, which represents one of the best results reported on these popular tasks

Investigating the robustness of a Hungarian medical dictation system under various conditions

This paper examines the susceptibility of a dictation system to various types of mismatches between the training and testing conditions. With these experiments we intend to find the best training configuration for the system and also to evaluate the efficiency of the speaker adaptation algorithm we use. The paper first presents the components of the dictation system, and then describes a set of training and recognition experiments where we vary the microphones and create gender-dependent and speaker-dependent models. In each case we examine how much the recognition performance can be improved further by speaker adaptation. We conclude that the best and most reliable scores can be obtained by using gender-dependent phone models in combination with speaker adaptation. Speaker adaptation results in great improvements in almost every case. However, our results do not confirm the assumption that the use of one microphone is better than the use of several.

RF Exposure Assessment Within Interphone

TS4-02 Abstract: Within the framework of the INTERPHONE Study, much work has gone into the development of radiofrequency (RF) exposure gradients and the estimation of associated uncertainties for the different head and neck tissues included in the case–control studies. Absorption of RF energy in the tissue volume of interest during a relevant time period is being taken as the main exposure quantity to be evaluated and allows for combining exposures at different frequencies and to different signal characteristics, eg, pulsed and continuous radio emissions. Specific absorption rate (SAR) of energy is a quantity that is routinely measured by mobile phone manufacturers to ensure compliance of their products with safety requirements. The testing involves the manipulation of a small field probe inside a phantom head shell filled with tissue-equivalent liquid while the phone is mounted in a defined position and radiates at its maximum power. In the case of compliance testing, the objective is to define the maximum average SAR occurring in any 10-g cube. However, for the purposes of INTERPHONE, SAR can then be integrated over any tissue volume of interest such as a region where a tumor was initiated and over a relevant time period. Different mobile phones produce different distributions of SAR inside the head; and INTERPHONE has put considerable effort into trying to group phones into a small number of categories that produce similar distributions based on their external observable characteristics and frequency band. Generic distributions have been developed to represent each of these classes so the SAR at a defined tumor location can be assessed by a lookup table. The output power of modern mobile phones can vary during a call, and this offers the potential for the environment in which a phone is used to influence its average output power and hence exposure. INTERPHONE has used a combination of software-modified phones (SMPs) and information from network operators to gather data on output power for a range of conditions such as indoor/outdoor, moving/stationary, urban/rural, different countries, and different network operators. There is also a need to consider whether there are any historical factors causing exposure to have changed during the period of exposure of the subject such as the move from analog to digital technology, the introduction of variable output powers, and the reducing size of mobile phones. Key dates for technologic changes influencing exposure have been collected for the network subscribed to as well as changes in the model of phone being used. In summary, the main information sources INTERPHONE is using to develop exposure indices for a particular case/control tumor are: 1. The initiation location, which is defined by neuroradiologists through an agreed reporting framework; 2. A database of generic SAR distributions from which the appropriate distribution is selected based on the phone make/model being used; 3. A database of generic phone output power distributions from which an applicable distribution is selected based on the call environment; and, 4. Data on the use of the mobile phone reported through a questionnaire.

Measurements of skin surface temperature during mobile phone use

We measured maximum temperature rises on the side of the face after 6 min of continuous mobile phone operation using two models of AMPS analog phones operating in the 835 MHz band and three early model GSM digital phones operating in the 900 MHz band. For the GSM phones the highest recorded temperature rise difference was 2.3 degrees C and for the AMPS phones it was 4.5 degrees C, both at locations on the cheek. The higher differential temperature rise between AMPS and GSM may reflect the higher maximum average operating power of AMPS (600 mW) versus GSM900 (250 mW). Additionally, we compared temperature changes at a consistent location on the cheek for an AMPS phone that was inoperative (-0.7 degrees C), transmitting at full power (+2.6 degrees C) and in stand-by mode (+2.0 degrees C). Our results suggest that direct RF heating of the skin only contributes a small part of the temperature rise and that most is due to heat conduction from the handset.

Temperature Increase in Human Heads Due to Different Models of Cellular Phones

The temperature increase in a realistic human head model exposed to five different cellular phone models is investigated by a bioheat equation and the finite-difference time-domain (FDTD) method at 900 and 1800 MHz, respectively. These five cellular phone models are greatly differ from each other in structure. The realistic human head model is used to investigate the temperature increase in the head affected by varying factors including; electric properties of human head tissues, hand absorption power effect, cellular phone models, homogeneous and inhomogeneous head models, cellular phone material, and the distance between the cellular phone and the head. Computed results show that the temperature increase in the head reaches the steady-state value for exposure time of about 20 minutes. For worst-case, the maximum temperature increase in the head is found to be 0.19° C at 900 MHz and 0.055° C at 1800 MHz for the inhomogeneous human head with six tissues exposed to a metallic handset held by a hand, with antenna output power of 0.6 W and 0.125 W, respectively. The maximum temperature increase in the head is far less than the threshold temperature increase of 4.5° C which can cause neuron damage.

Comparisons of Computed Mobile Phone Induced SAR in the SAM Phantom to That in Anatomically Correct Models of the Human Head.

The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, SubCommittee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.