bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of Voicing Cues by Children With Early Otitis Media With and Without Language Impairment
Authors: Groenen Paul , Crul Thom , Maassen Ben , Bon Wim van
Published: August 2014

Research on the relationship between early otitis media with effusion (OME), language impairment, and central auditory processing has been equivocal. Identification and discrimination tasks provide us with a sensitive method of assessing speech perception on both an auditory and a phonetic level. The present study examined identification and discrimination of initial bilabial stop consonants differing in voicing by 9-year-old children with a history of severe OME. The groups studied were controlled for language impairment. The ability of these children to perceive major and minor voicing cues was examined using multiple voicing cues. Long-term effects of OME were found for both identification and discrimination performance. Children with OME produced an overall inconsistency in categorization, which suggests poorer phonetic processing. Discrimination was measured by means of “just noticeable differences” (JND). Children with early OME experience demonstrated a greater mean JND than children without early OME experience. Finally, in cases of language impairment with early OME, there was no additional deterioration of auditory or phonetic processing. It appears that either early OME or language impairment can lead to poorer perception.
The Actifier
Authors: Finan Donald S. , Barlow Steven M.
Published: August 2014

A new device for the stimulation of intraoral tissues in human neonates is described. This instrument, known as anactifier, features a wide frequency range for mechanical stimulation, integrated multichannel electomyographic electrode pairs, and the capacity for transducing jaw compression during non-nutritive sucking behavior. The stimulus/recording interface consists of a modified pacifier. The actifier has been used to investigate the responsiveness of the sucking central pattern generator in human infants to mechanical perturbation.
Auditory Lexical Decisions of Children With Specific Language Impairment
Authors: Edwards Jan , Lahey Margaret
Published: August 2014

To determine whether children with specific language impairment (SLI) take longer than age peers to recognize sequences of sounds that represent words in their lexicon, we compared auditory lexical decision times of children with SLI to those of typically developing age peers. Children with SLI were significantly slower than peers, but speed of word recognition was not correlated with measures of language comprehension for children with SLI. Furthermore, time to detect an auditory signal and initiate a vocal response did not account for the differences between groups. Possible interpretations of the results are discussed with two explanations—differences between groups in task-related factors that stressed processing capacity or in the nature of phonetic/phonological representations—seeming more likely than others.
Two Models of Grammar Facilitation in Children With Language Impairments
Authors: Fey Marc E. , Cleave Patricia L. , Long Steven H.
Published: August 2014

Fey, Cleave, Long, and Hughes (1993) demonstrated the effectiveness of two 5-month interventions for preschoolers with problems in expressive grammar. This article reports the results of an additional 5-month intervention phase for 18 of the original participants. Results indicated that although participants improved during Phase 2, improvements generally were not as strong as those noted for Phase 1. Gains were larger and more consistent for children who received the relatively costly clinician-administered approach than for those who received a less expensive parent-administered intervention. The parent intervention was successful in helping parents to use sentence recasts, and especially so for parents of children at relatively early stages of grammatical development. Finally, children who were dismissed after a highly successful treatment Phase 1 generally exhibited no gains over the no-treatment Phase 2.
Speech Breathing and the Lombard Effect
Authors: Winkworth Alison L. , Davis Pamela J.
Published: August 2014

Respiratory measurements were made using linearized magnetometers placed antero-posteriorly over the rib cages and abdomens of five healthy young women. Background noise was introduced over headphones simultaneously as "babble" presented binaurally at 55 dB ("moderate noise") and 70 dB ("high noise"). Speech during oral reading and spontaneous monologue was transduced with a microphone positioned near the lips, from which a speaking intensity signal (dBA) was derived. Subjects were instructed to speak during the noise conditions, but no instruction was given to alter speaking intensity. Compared with a "no noise" condition, the speaking intensities of all the subjects increased significantly for both speech tasks in the moderate and high noise conditions, thereby replicating the well-documented Lombard effect. No consistent trend of lung volume change was observed, in contrast to the linear increases in speech intensity as the noise level increased. For the higher speech intensities during the moderate and high noise conditions both initiation and termination lung volumes either increased or decreased. These preliminary findings suggest that when speech intensity is increased following the introduction of noise via headphones rather than by specific instructions to speak more loudly, speakers employ variable lung volume strategies for intensity control.
Identifying the Authoritative Judgments of Stuttering
Authors: Ingham Roger J. , Cordes Anne K.
Published: August 2014

Reliable and accurate stuttering measurement depends on the existence of unambiguous descriptions or exemplars of stuttered and nonstuttered speech. The development of clinically meaningful and useful exemplars, in turn, requires determining whether persons who stutter judge the same speech to be stuttered that other observers judge to be stuttered. The purpose of these experiments, therefore, was to compare stuttering judgments from several sources: 15 adults who stutter, judging their own spontaneous speech; the same adults who stutter, judging each other's speech; and a panel of 10 authorities on stuttering research and treatment. Judgments were made under several conditions, including selfjudgments made while the speaker was talking and self- and other-judgments made from recordings in continuous and interval formats. Results showed substantial differences in stuttering judgments across speakers, judges, and judgment conditions, but across-task comparisons were complicated by low selfagreement for many judges. Some intervals were judged consistently by all judges to be Stuttered or Nonstuttered, across multiple conditions, but many other intervals were either not assigned replicable judgments or were consistently judged to be Nonstuttered by the speaker who had produced them but were not assigned consistent judgments by other judges. The implications of these findings for stuttering measurement are considered.
Response Latency and Verbal Complexity
Authors: Evans Julia L. , Viele Kert , Kass Robert E.
Published: August 2014

Within-subject statistical modeling techniques were employed to investigate individual differences in the extent to which two possible indicators of processing time predicted changes in utterance complexity during spontaneous discourse for 10 children ages 7;1 to 10;1 with specific language impairments (SLI) who differed in receptive language abilities. The two indicators of processing time that were modeled were response latency and the use of a specific discourse marker (Verbal Pause) that provided children with additional time to respond. Longer response latencies were not a strong predictor of increased utterance length for any of the children. However, results indicated that children with better receptive skills used substantially more verbal pauses than children with both expressive and receptive deficits and that the use of these pauses was a strong predictor of increased utterance length for children with better comprehension skills.
Lip and Jaw Kinematics in Bilabial Stop Consonant Production
Authors: Löfqvist Anders , Gracco Vincent L.
Published: August 2014

This paper reports two experiments, each designed to clarify different aspects of bilabial stop consonant production. The first one examined events during the labial closure using kinematic recordings in combination with records of oral air pressure and force of labial contact. The results of this experiment suggested that the lips were moving at a high velocity when the oral closure occurred. They also indicated mechanical interactions between the lips during the closure, including tissue compression and the lower lip moving the upper lip upward. The second experiment studied patterns of upper and lower lip interactions, movement variability within and across speakers, and the effects on lip and jaw kinematics of stop consonant voicing and vowel context. Again, the results showed that the lips were moving at a high velocity at the onset of the oral closure. No consistent influences of stop consonant voicing were observed on lip and jaw kinematics in five subjects, nor on a derived measure of lip aperture. The overall results are compatible with the hypothesis that one target for the lips in bilabial stop production is a region of negative lip aperture. A negative lip aperture implies that to reach their virtual target, the lips would have to move beyond each other. Such a control strategy would ensure that the lips will form an air tight seal irrespective of any contextual variability in the onset positions of their closing movements.
Naming Difficulties in Language-Disabled Children
Authors: Faust Miriam , Dimitrovsky Lilly , Davidi Shira
Published: August 2014

The "tip of the tongue" (TOT) paradigm in a picture-naming task was presented to 14 children with language disabilities (LD) and 14 children without language disabilities (ND). Although the two groups did not differ in the semantic information they had on words they could not fully retrieve, the LD children had less valid and more invalid phonological information. They also had fewer correct responses and spontaneous recalls, more "Don't Know"s (DK) and TOTs, and less accurate "feeling of knowing" (FOK) judgments. These results, demonstrating dissociation between the semantic and phonological levels of word representation, support a two-stage model of word retrieval. These findings are evidence in favor of a phonological treatment approach for naming problems in LD children.
Central Auditory Processing Disorder in School-Aged Children
Authors: Cacace Anthony T. , McFarland Dennis J.
Published: August 2014

The rationale to evaluate for central auditory processing disorder (CAPD) in schoolaged children is based on the assumption that an auditory-specific perceptual deficit underlies many learning problems including specific reading and language disabilities. A fundamental issue in this area is whether convincing empirical evidence exists to validate this proposition. Herein, we consider the issue of modality specificity by examining the extent to which reading, language, and attention disorders in schoolaged children involve perceptual dysfunctions limited to a single sensory modality. Difficulty in validating CAPD as a diagnostic label is due in large part to use of the unimodal inclusive framework, which has biased the diagnosis to favor sensitivity of test results over documenting the specificity of the deficit. Indeed, empirical research documenting modality-specific auditory-perceptual dysfunction in this population is scarce. Therefore, the existing literature on this topic has not clarified the "true" nature of the problem, and has left many questions about this disorder unanswered. It is argued that demonstrating modality specificity is one way to rule out supramodal disorders as explanations for observed dysfunction. Multimodal perceptual testing is one logical approach to help clarify this area of investigation.
Effect of Extended Exposure to Frequency-Altered Feedback on Stuttering During Reading and Monologue
Authors: Armson Joy , Stuart Andrew
Published: August 2014

An
ABA
time series design was used to examine the effect of extended, continuous exposure to frequency-altered auditory feedback (FAF) during an oral reading and monologue task on stuttering frequency and speech rate. Twelve adults who stutter participated. A statistically significant decrease in number of stuttering events, an increase in number of syllables produced, and a decrease in percent stuttering was observed during the experimental segment relative to baseline segments for the oral reading task. In the monologue task, there were no statistically significant differences for the number of stuttering events, number of syllables produced, or percent stuttering between the experimental and baseline segments. Varying individual patterns of response to FAF were evident during the experimental segment of the reading task: a large consistent reduction in stuttering, an initial reduction followed by fluctuations in amount of stuttering, and essentially no change in stuttering frequency. Ten of 12 participants showed no reduction in stuttering frequency during the experimental segment of the monologue task. These findings have ramifications both for the clinical utilization of FAF and for theoretical explanations of fluency-enhancement.
Children's Imitations of Intonation Contours
Authors: Snow David
Published: August 2014

Perceptual evidence suggests that young children do not imitate adult-modeled intonation patterns with a rising pitch contour (rising tones) as well as those with a falling pitch contour (falling tones). To investigate the acoustic basis of this uneven imitation pattern, 10 4-year-old children were asked to imitate short sentences with falling and rising tones in 4 sentence contexts called "intonation groups." The results indicated that the children used more falling tones than adults in most intonation groups. When the children matched the adult-modeled contour direction (falling or rising), the children's speed of pitch change was comparable to that of adults in the falling tones of final intonation groups and in the rising tones of nonfinal groups, but was slower than that of adults in the complementary environments. In a manner consistent with previously reported perceptual data, the instrumental findings indicate that rising tones may be more difficult for 4-year-old children to produce than falling tones. The results additionally suggest that children's intonation is sensitive not only to the direction of tonal contours but also to their position in sentence-final versus nonfinal intonation groups.
Lip EMG Activity During Vowel Production in Apraxia of Speech
Authors: Hough Monica Strauss , Klich Richard J.
Published: August 2014

This investigation examined the timing relationships of EMG activity underlying vowel production in 2 normal individuals and in 2 individuals with marked-tosevere apraxia of speech of approximately two-and-one-half years duration. The timing of lip muscle activity was investigated in monosyllabic words embedded in phrases and in syllable word stems as a function of changes in word length. Specifically, the onset and offset of EMG activity of lip muscles used for production of /u/ in the monosyllables and word stems were examined. The results revealed that the relative amounts of time devoted to onset and offset of EMG activity for lip rounding are disorganized in apraxia of speech. Word length appeared to affect the timing of the onset of muscle activity for both the normal speakers and the speakers with apraxia of speech. Word length also influenced the offset of muscle activity, but its effect was less systematic for the speakers with apraxia of speech. The findings suggest that termination of EMG activity may be at least as disturbed as the initiation of EMG activity in apraxia of speech.
Interactions of African American Infants and Their Mothers
Authors: Wallace Ina F. , Roberts Joanne E. , Lodder Diane E.
Published: August 2014

The relationships between aspects of mother-infant interaction and both communication and cognitive skills at 1 year of age were examined in 92 African American dyads, of whom 64 (70%) fell below the poverty line. Ratings of warmth, sensitivity, responsiveness, encouragement of initiative, stimulation, and elaborativeness during a semistructured play interaction were correlated with measures of global cognition, expressive and receptive communication, and communication use. The overall quality of the home environment and maternal ratings of stimulation and elaborativeness were the most consistent correlates of infant communication measures. Relationships were stronger in middle-income than lower-income dyads. These results support the linkage of didactic and functional aspects of maternal behavior to cognitive and communication skills at 1 year of age for African American infants.
Fourteen-Year Follow-Up of Children With and Without Speech/Language Impairments
Authors: Johnson Carla J. , Beitchman Joseph H. , Young Arlene , Escobar Michael , Atkinson Leslie , Wilson Beth , Brownlie E. B. , Douglas Lori , Taback Nathan , Lam Isabel , Wang Min
Published: August 2014

This report concerns the speech and language outcomes of young adults (
N
= 242) who participated in a 14-year, prospective, longitudinal study of a community sample of children with (
n
= 114) and without (
n
= 128) speech and/or language impairments. Participants were initially identified at age 5 and subsequently followed at ages 12 and 19. Direct assessments were conducted in multiple domains (communicative, cognitive, academic, behavioral, and psychiatric) at all three time periods. Major findings included (a) high rates of continued communication difficulties in those with a history of impairment; (b) considerable stability in language performance over time; (c) better long-term outcomes for those with initial speech impairments than for those with language impairments; and (d) more favorable prognoses for those with specific language impairments than for those with impairments secondary to sensory, structural, neurological, or cognitive deficits. These general conclusions held when either a liberal or a more stringent criterion for language impairment was employed. Some of these findings are consistent with those from earlier follow-up studies, which used less optimal methods. Thus, the present replication and extension of these findings with a sound methodology enables greater confidence in their use for prognostic, planning, and research purposes.
Older Adult Performance on the Communication Profile for the Hearing Impaired
Authors: Garstecki Dean C. , Erler Susan F.
Published: August 2014

Gender difference in auditory function with age is well documented. However, little is known about the influence of interacting sensory, psycho-social, and economic variables on adjustment to hearing loss. Adjustment to acquired, mild-to-moderate hearing loss by advantaged older women and men was examined using the Communication Profile for the Hearing Impaired (CPHI) (Demorest & Erdman, 1987). Correlational analyses revealed relationships between scales to be similar for women and men. Controlling for socio-demographic and hearing variables, group responses for the majority of CPHI scales did not differ significantly. Six scales differed significantly, and those results are discussed. When compared to men, women assigned greater importance to effective social communication, were more likely to use nonverbal communication strategies, reported greater anger and stress, and reported greater problem awareness and less denial associated with hearing loss. The CPHI is a useful tool for specifying parameters of perceived communication handicap for both older men and women. Findings underscore the need to consider gender-specific self-assessment of communication and personal adjustment in clinical management of older adults with age-related hearing loss.
Comparison of Risk of Conductive Hearing Loss Among Three Ethnic Groups of Arctic Audiology Patients
Authors: Moore Jan Allison
Published: August 2014

The purpose of the study was to investigate the relative contributions of age, gender, ethnic background, and a history of middle ear disease on the amount of conductive hearing impairment among native and non-native audiology patients in the Canadian North. A second goal of the study was to determine risk factors for conductive hearing loss in the patients studied. Three ethnic groups were represented among the 3,094 patients: Inuit, American Indian, and non-native. Loglinear and logit statistical models were applied, and these data were best explained by a 3-way interaction of history of middle ear disease, ethnic group, and hearing loss, and the 2-way interaction of age and hearing loss. The Inuit appear to be at higher risk for conductive hearing impairment than the other ethnic groups. Conductive hearing loss also appears to increase as age increases through the teenage years for all the patients regardless of ethnic group membership. Preschoolers were at the lowest risk for conductive hearing loss. The trend for the amount of hearing impairment to increase throughout childhood suggests that children living in the Arctic may manifest a unique and more serious form of the disease not often observed in audiology patients who are Caucasian in southern Canada or the United States or that they may be exposed to additional risk factors.
Balancing Bilinguals
Authors: Kohnert Kathryn J. , Bates Elizabeth , Hernandez Arturo E.
Published: August 2014

The present study investigated developmental changes in lexical production skills in early sequential bilinguals, in both Spanish (L1) and English (L2), exploring the effects of age, years of experience, and basic-level cognitive processing (specifically the ability to resist interference) within a timed picture-naming task. To assess resistance to interference, naming was compared in low competition (blocked-single language) vs. high competition (mixed-alternating language) conditions. Participants were 100 individuals, 20 at each of 5 different age levels (5–7, 8–10, 11–13, 14–16, & young adults). All had learned Spanish as a first language in the home, with formal English experience beginning at 5 years. Gains were made in both languages across age. However, there was a developmental crossover from Spanish dominance in the youngest children, through a period of relatively balanced Spanish and English skills in middle childhood, culminating in a clear pattern of English dominance among adolescents and young adults. Although all groups experienced a greater slowing of response times in the mixed-language condition relative to the blocked-language condition, developmental changes in the pattern of speed-accuracy trade-offs in the mixed condition can be interpreted to reflect a change in the ability to resist cognitive interference during word production.
Cross-Modal Generalization Effects of Training Noncanonical Sentence Comprehension and Production in Agrammatic Aphasia
Authors: Jacobs Beverly J. , Thompson Cynthia K.
Published: August 2014

The cross-modal generalization effects of training complex sentence comprehension and complex sentence production were examined in 4 individuals with agrammatic Broca’s aphasia who showed difficulty comprehending and producing complex, noncanonical sentences. Object-cleft and passive sentences were selected for treatment because the two are linguistically distinct, relying on
wh
- and NP movement, respectively (Chomsky, 1986). Two participants received comprehension training, and 2 received production training using linguistic specific treatment (LST). LST takes participants through a series of steps that emphasize the verb and verb argument structure, as well as the linguistic movement required to derive target sentences. A single-subject multiple-baseline design across behaviors was used to measure acquisition and generalization within and across sentence types, as well as cross-modal generalization (i.e., from comprehension to production and vice versa) and generalization to discourse. Results indicated that both treatment methods were effective for training comprehension and production of target sentences and that comprehension treatment resulted in generalization to spoken and written sentence production. Sentence production treatment generalized to written sentence production only; generalization to comprehension did not occur. Across sentence types generalization also did not occur, as predicted, and the effects of treatment on discourse were inconsistent across participants. These data are discussed with regard to models of normal sentence comprehension and production.
Spontaneous Language of Children With Specific Neurological Syndromes
Authors: Levy Y. , Tennenbaum A. , Ornoy A.
Published: August 2014

This paper presents data concerning the early phases of language development in 8 children with congenital neurological syndromes (NS) who are cognitively impaired. The children are native speakers of Hebrew, and their verbal achievements assessed on normative tests are below their age level. The children’s spontaneous speech was analyzed with respect to 13 different language variables known to be diagnostic of a child’s developmental level. No differences were found between the children and their language-matched controls on 10 grammatical variables. The groups differed, however, in number of pragmatic errors, errors of word choice, and errors of gender marking on animate nouns. Profile analysis was done through the use of POSAC (partial order scalogram analysis by base coordinates; Shye, 1985 Shye, Elizur, & Hoffman, 1994). The analysis did not reveal differences between the children with NS and the controls.

These findings suggest the possibility of a mechanism that is functionally akin to brain plasticity. Such a mechanism will guarantee the preservation of basic linguistic skills in children with NS.
A Study of F1 Coarticulation in VCV Sequences
Authors: Recasens Daniel , Pallarès Maria Dolors
Published: August 2014

This study investigates F1 coarticulatory patterns in a large sample of VCV sequences with 7 consonants and 2 vowels uttered by 5 Catalan speakers. Measures of the size and the temporal extent of anticipatory and carryover coarticulation were obtained for the consonantal effects during the adjacent vowels, for the vocalic effects at the consonantal period, and during each transconsonantal vowel; F1 coarticulatory patterns are interpreted in the light of coarticulation data for the jaw and for dorsopalatal contact and F2 reported in the literature. Results show that consonantal effects reflect trends in lingual and jaw coarticulation, whereas vocalic effects are mostly in agreement with jaw coarticulatory trends. This finding is consistent with the view that consonantal and vocalic gestures overlap in VCV sequences and are ruled by relatively independent articulatory subsystems.
Multivariate Statistical Analysis of Flat Vowel Spectra With a View to Characterizing Dysphonic Voices
Authors: Schoentgen Jean , Bensaid Mounir , Bucella Fabrizio
Published: August 2014

The aim of this article is to show how dysphonic voices can be characterized by means of a multivariate statistical analysis of flat vowel spectra. The spectral contour was obtained by means of a wavelet transform of the logarithmic magnitude spectrum, which was subsequently flattened to remove interspeaker variability related to the excitation and vocal tract filter functions. The results of the statistical analysis of flat spectra were the following. Firstly, principal components analysis produced markers that separated noisy from clean spectra. Secondly, the heuristic search for harmonic peaks or interharmonic dips could be omitted. Thirdly, conventional spectral markers of noise appeared as special instances of the markers that were derived statistically. Fourthly, the levels of visually assigned hoarseness and the first two principal components were significantly correlated. The assignment of different levels of (visual) hoarseness to different vowel timbres could be explained by the variability associated with the spectral contour.
Aprosodia and Its Treatment
Authors: Leon Susan A. , Rodriguez Amy D.
Published: August 2014

Aprosodia is a deficit in comprehending or expressing variations in tone of voice used to express both linguistic and emotional information. Affective aprosodia refers to a specific deficit in producing or comprehending the emotional or affective tones of voice. Aprosodia is most commonly associated with right hemisphere strokes; however, it may also result from other types of brain damage such as traumatic brain injury. Although research investigating hemispheric lateralization of prosody continues, there is strong evidence that most aspects of affective prosody are directed by the right hemisphere. Disorders of emotional communication can have a significant impact on quality of life for those affected and their families. However, there has been relatively little research regarding treatment for this disorder. Recently, 14 individuals were treated for affective aprosodia using two treatments, one based on cognitive-linguistic cues and the other on imitation of prosodic modeling. Most of the participants responded to at least one of the two treatments, and a refinement of the treatments are currently underway. Because researchers are finding support for the hypothesis that expressive aprosodia can result from a motor deficit, the refined treatment incorporates principles of motor learning to enhance imitation of prosodic models, as well as cognitive-linguistic cues.
The Pediatric Lung and Aspiration
Authors: Simon Marni , Collins Melanie Sue
Published: August 2014

This article offers an over view of lung development, physiology, and evaluation of lung damage due to aspiration. Considerations specific to pediatric patients are discussed.
Soft‐output space‐time block coded spatial modulation
Authors: Govender Rasigan , Pillay Narushan , Xu HongJun
Published: August 2014

Space‐time block coded spatial modulation (STBC‐SM) is a recently proposed multiple‐input–multiple‐output transmission scheme, which combines spatial modulation (SM) and Alamouti's space‐time block code (STBC) in such a manner so as to retain the primary advantages of SM and STBC, while avoiding their drawbacks, resulting in an improved system error performance. In this study, the authors propose a soft‐output maximum‐likelihood (ML) detector (SOMLD) and a soft‐output low‐complexity near‐ML detector (SOLCD) for STBC‐SM transmission. Monte‐Carlo simulations demonstrate that the error performance of the proposed schemes are able to closely match that of the hard decision ML detector for uncoded channel conditions, while significant improvement in error performance is demonstrated for coded systems. Furthermore, compared with SOMLD, SOLCD imposes a significantly lower computational complexity, while achieving near‐ML error performance.
Iterative frequency‐domain fractionally spaced receiver for zero‐padded multi‐carrier code division multiple access systems
Authors: Yan Yanxin , Gong Yi , Ma Maode , Shi Qinghua
Published: August 2014

In this study, the authors propose an improved frequency‐domain fractionally spaced (FDFS) minimum mean square error (MMSE) receiver for zero‐padded multi‐carrier code division multiple access (MC‐CDMA) systems when the guard interval is not enough to avoid the inter‐symbol interference (ISI) caused by the multipath channel. The proposed novel iterative FDFS‐based receivers firstly reconstruct the received symbol to reduce the ISI and then followed by the FDFS‐based equalisers to minimise the effect of ISI and inter‐carrier interference (ICI) caused by carrier frequency offset (CFO) and Doppler shifts. A few iterations are performed to achieve the expected bit error rate (BER) performance. To reduce the receiver complexity, the novel simplified diagonal FDFS‐based receivers with a fixed noise variance are developed with slight performance degradation. The proposed iterative receivers have never been studied in the existing literature. Simulation results show that the proposed iterative FDFS‐based receivers can significantly improve the BER performance of the conventional FDFS‐MMSE receiver in severe multiple interferences environments caused by multipath, CFO and Doppler shift.
Wheeled human transportation vehicle implementation using output recurrent fuzzy control strategy
Authors: Chiu Chih‐Hui , Chang Chun‐Chieh
Published: August 2014

Human being assistant transportation systems have received much attention in recent years. This study proposes a wheeled human transportation vehicle (WHTV). Two‐wheeled vehicles have been known as powerful transporters for urban areas. Based on a low‐level microprocessor, a WHTV is designed and implemented in this study. Moreover, a Mamdani‐like output recurrent fuzzy controller (MLORFC) is used to control the WHTV in this study. As the MLORFC obtains system dynamics, it is better than the traditional Mamdani‐type fuzzy controllers in terms of dynamic response. A necessary condition based on the Lyapunov stability analysis is established to guarantee the system stability. The recurrent weights are tuned on‐line using the dynamic gradient descent method. The learning rates of the recurrent weights are automatically settled based on a Lyapunov analytical method to achieve the system error convergence. The experiment results in Section 4 show that the conveyance platform can stably move under the proposed control strategy.
Approximation‐based adaptive control of uncertain non‐linear pure‐feedback systems with full state constraints
Authors: Kim Bong Su , Yoo Sung Jin
Published: August 2014

This study proposes an adaptive approximation‐based control approach for non‐linear pure‐feedback systems in the presence of full state constraints. Completely non‐affine non‐linear functions are considered and assumed to be unknown. The dynamic surface design based on integral barrier Lyapunov functionals is provided to achieve both the desired tracking performance and the constraints satisfaction, in consideration of the full‐state‐constrained non‐affine non‐linearities. In this design procedure, simple sufficient conditions for choosing control gains, which can be checked off‐line, are established to guarantee the feasibility of the controller. The function approximation technique is employed to estimate unknown non‐linearities induced from the controller design procedure where the adaptive laws using the projection operator are designed to ensure the boundedness of the function approximators in the feasibility conditions. It is shown that all the signals in the closed‐loop system are uniformly ultimately bounded and the tracking error converges to an adjustable neighbourhood of the origin while all state variables always remain in the constrained state space.
Improving dynamic range of software‐defined radio receivers for multi‐carrier wireless systems
Authors: Cruz Pedro Miguel , Carvalho Nuno Borges
Published: August 2014

This study presents an architecture to increase the instantaneous dynamic range of multi‐carrier wideband digital receivers. The proposed topology includes a directional coupler followed by two parallel analog‐to‐digital converters and digital signal processing to reconstruct the signal. It will be shown that the proposed technique is able to increase the dynamic range of software‐defined radio (SDR) receivers for multiband signals presenting certain statistical patterns. The concept is validated by simulations and measurements of a real SDR front‐end receiver for multiband communications scenario, which will demonstrate improvements in the order of 6 dB when compared to existing alternatives.
Constraining directional modulation transmitter radiation patterns
Authors: Ding Yuan , Fusco Vincent F.
Published: August 2014

An iterative pattern synthesis approach for directional modulation (DM) transmitters is presented in this study. Unlike all previous work, this study offers the first discussion on constraining DM transmitter far‐field radiation patterns so that energy is primarily concentrated in the spatial direction where low bit error rate is to be achieved, while interference projected along other directions is reduced.
Corner‐fed dual‐band circularly polarised antenna
Authors: Chang The‐Nan , Lin Jyun‐Ming
Published: August 2014

A slot‐coupled dual‐band circularly polarised (CP) antenna is presented for 1.575 and 2.45 GHz bands. The antenna is composed of a split‐patch surrounded by a split‐ring. The slits can be lined‐up toward the centre of the antenna to generate dual CP bands with opposite senses (left‐hand and right‐hand waves). To generate dual CP bands with the same sense, the slits on the patch is located orthogonal to the slits on the ring. In the coupled feed, the slot is a square in shape and is corner‐coupled to a microstrip line. The lengths of the slits are tuned for good CP operations at both bands. Good match is obtained on both bands by adding stubs to the feeding microstrip line.
Pencil beam radiation pattern from a single‐layer substrate‐integrated waveguide leaky‐wave antenna with simple feeding
Authors: Martinez‐Ros Alejandro Javier , Gómez‐Tornero José Luis , Goussetis George
Published: August 2014

A central feeding array radiating at broadside and manufactured in substrate‐integrated waveguide (SIW) technology is shown in this work. The single‐layer array consists of N = 8 line‐source leaky‐wave antennas (LWAs), which are designed to satisfy the splitting condition (α = β) of the leaky mode. The LWAs are arranged in a radial configuration, in this manner, by properly designing the SIW width W and the spacing between SIW vias P for each SIW LWA, the leaky mode can be independently controlled to fulfil the splitting condition, and all the individual beams from each SIW LWA can merge into one at broadside direction (θ = 0°) for a given design frequency. The two‐dimensional radiating surface allows obtaining a pencil beam radiation pattern, which is linearly polarised because of the radial arrangement. A prototype with a radiating length of LA = 60 mm for each SIW LWA, and a total radius of R = 73 mm has been manufactured for a design frequency of 15 GHz. Input matching, gain and radiation patterns at several planes have been measured and compared with full‐wave simulations, obtaining good agreement between them.
Hexagonal fractal ultra‐wideband antenna using Koch geometry with bandwidth enhancement
Authors: Tripathi Shrivishal , Mohan Akhilesh , Yadav Sandeep
Published: August 2014

In this study, a design approach to achieve multiresonance phenomena in ultra‐wideband (UWB) bandwidth using fractal geometry is investigated. The introduction of Koch fractal geometry in monopole as well as in the ground plane of the antenna generates additional resonances, which helps to achieve entire UWB operational bandwidth. Therefore the bandwidth is increased up to 122%. Moreover, the fractal nature of the antenna also facilitates to obtain the stable radiation pattern. The compact dimension 31 mm × 28 mm of the antenna exhibits nearly omnidirectional radiation pattern, with good reflection coefficient over the entire UWB frequency range. The proposed prototype is fabricated and its measured results are in good agreement with the simulated one. The time‐domain analysis of the antenna is performed and it is found that fidelity factor is better than 0.81, which shows good pulse preserving capability of the antenna.
Tuning of noble metal work function with organophosphonate nanolayers
Authors: Ramanath Ganpati , Kwan Matthew , Chow P. K. , Quintero Y. Cardona , Mutin P. H. , Ramprasad R.
Published: August 2014

We demonstrate that weak chemical interactions between untethered moieties in molecular nanolayers on metal surfaces can strongly influence the effective work function Φeff. Electron spectroscopy shows that nanolayers of mercaptan-anchored organophosphonates on Au and Pt decrease Φeff. The measured Φeff shifts correlate with the chemical state of phosphonic acid moieties, and scale with molecular length. These results are contrary to predictions of ab initio calculations of monolayer-capped surfaces, but are consistent with calculations of bilayer-capped surfaces with face-to-face hydrogen-bonded phosphonic acid moieties. Our findings indicate that intra-layer bonding and layering in molecular nanolayers can be key to tailoring heterointerfacial electronic properties for applications.
Development of a dual MCP framing camera for high energy x-rays
Authors: Izumi N. , Hall G. N. , Carpenter A. C. , Allen F. V. , Cruz J. G. , Felker B. , Hargrove D. , Holder J. , Kilkenny J. D. , Lumbard A. , Montesanti R. , Palmer N. E. , Piston K. , Stone G. , Thao M. , Vern R. , Zacharias R. , Landen O. L. , Tommasini R. , Bradley D. K. , Bell P. M.
Published: August 2014

Recently developed diagnostic techniques at LLNL require recording backlit images of extremely dense imploded plasmas using hard x-rays, and demand the detector to be sensitive to photons with energies higher than 50 keV [R. Tommasini et al., Phys. Phys. Plasmas 18, 056309 (2011); G. N. Hall et al., “AXIS: An instrument for imaging Compton radiographs using ARC on the NIF,” Rev. Sci. Instrum. (these proceedings)]. To increase the sensitivity in the high energy region, we propose to use a combination of two MCPs. The first MCP is operated in a low gain regime and works as a thick photocathode, and the second MCP works as a high gain electron multiplier. We tested the concept of this dual MCP configuration and succeeded in obtaining a detective quantum efficiency of 4.5% for 59 keV x-rays, 3 times larger than with a single plate of the thickness typically used in NIF framing cameras.
Surface structures of In-Pd intermetallic compounds. I. Experimental study of In thin films on Pd(111) and alloy formation
Authors: McGuirk G. M. , Ledieu J. , Gaudry É. , de Weerd M.-C. , Fournée V.
Published: August 2014

A combination of experimental methods was used to study the structure of In thin films deposited on the Pd(111) surface and the alloying behavior. X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and scanning tunneling microscopy results indicate that surface alloying takes place at room temperature. Below 2 monolayer equivalents (MLEs), the LEED patterns show the formation of three rotational domains of InPd(110) of poor structural quality on top of the Pd(111) substrate. Both core-levels and valence band XPS spectra show that the surface alloy does not yet exhibit the electronic structure characteristic of the 1:1 intermetallic compound under these conditions. Annealing the 1 MLE thin film up to 690 K yields to a transition from a multilayer InPd near-surface intermetallic phase to a monolayer-like surface alloy exhibiting a well ordered (\documentclass[12pt]{minimal}\begin{document}$\sqrt{3}\break\times \sqrt{3}$\end{document}3×3) \documentclass[12pt]{minimal}\begin{document}$\textsc {R30}^{\circ }$\end{document}R30∘ superstructure and an estimated composition close to In2Pd3. Annealing above 690 K leads to further In depletion and a (1 × 1) pattern is recovered. The (\documentclass[12pt]{minimal}\begin{document}$\sqrt{3}\times \sqrt{3}$\end{document}3×3) \documentclass[12pt]{minimal}\begin{document}$\textsc {R30}^{\circ }$\end{document}R30∘ superstructure is not observed for thicker films. Successive annealing of the 2 MLE thin film leads the progressive disappearance of the InPd diffraction spots till a sharp (1 × 1) pattern is recovered above 690 K. In the high coverage regime (from 4 to 35 MLE), the formation of three rotational domains of a bcc-In7Pd3 compound with (110) orientation is observed. This In-rich phase probably grows on top of interfacial InPd(110) domains and is metastable. It transforms into a pure InPd(110) near-surface intermetallic phase in a temperature range between 500 and 600 K depending on the initial coverage. At this stage, the surface alloy exhibits core-level chemical shifts and valence band (VB) spectra identical to those of the 1:1 InPd intermetallic compound and resembling Cu-like density of states. Annealing at higher temperatures yields to a decrease of the In concentration in the near-surface region to about 20 at.% and a (1 × 1) LEED pattern is recovered.
Accurate measurement of relative tilt and azimuth angles in electron tomography: A comparison of fiducial marker method with electron diffraction
Authors: Hayashida Misa , Malac Marek , Bergen Michael , Egerton Ray F. , Li Peng
Published: August 2014

Electron tomography is a method whereby a three-dimensional reconstruction of a nanoscale object is obtained from a series of projected images measured in a transmission electron microscope. We developed an electron-diffraction method to measure the tilt and azimuth angles, with Kikuchi lines used to align a series of diffraction patterns obtained with each image of the tilt series. Since it is based on electron diffraction, the method is not affected by sample drift and is not sensitive to sample thickness, whereas tilt angle measurement and alignment using fiducial-marker methods are affected by both sample drift and thickness. The accuracy of the diffraction method benefits reconstructions with a large number of voxels, where both high spatial resolution and a large field of view are desired. The diffraction method allows both the tilt and azimuth angle to be measured, while fiducial marker methods typically treat the tilt and azimuth angle as an unknown parameter. The diffraction method can be also used to estimate the accuracy of the fiducial marker method, and the sample-stage accuracy. A nano-dot fiducial marker measurement differs from a diffraction measurement by no more than ±1°.
Stochastic many-body perturbation theory for anharmonic molecular vibrations
Authors: Hermes Matthew R. , Hirata So
Published: August 2014

A new quantum Monte Carlo (QMC) method for anharmonic vibrational zero-point energies and transition frequencies is developed, which combines the diagrammatic vibrational many-body perturbation theory based on the Dyson equation with Monte Carlo integration. The infinite sums of the diagrammatic and thus size-consistent first- and second-order anharmonic corrections to the energy and self-energy are expressed as sums of a few m- or 2m-dimensional integrals of wave functions and a potential energy surface (PES) (m is the vibrational degrees of freedom). Each of these integrals is computed as the integrand (including the value of the PES) divided by the value of a judiciously chosen weight function evaluated on demand at geometries distributed randomly but according to the weight function via the Metropolis algorithm. In this way, the method completely avoids cumbersome evaluation and storage of high-order force constants necessary in the original formulation of the vibrational perturbation theory; it furthermore allows even higher-order force constants essentially up to an infinite order to be taken into account in a scalable, memory-efficient algorithm. The diagrammatic contributions to the frequency-dependent self-energies that are stochastically evaluated at discrete frequencies can be reliably interpolated, allowing the self-consistent solutions to the Dyson equation to be obtained. This method, therefore, can compute directly and stochastically the transition frequencies of fundamentals and overtones as well as their relative intensities as pole strengths, without fixed-node errors that plague some QMC. It is shown that, for an identical PES, the new method reproduces the correct deterministic values of the energies and frequencies within a few cm−1 and pole strengths within a few thousandths. With the values of a PES evaluated on the fly at random geometries, the new method captures a noticeably greater proportion of anharmonic effects.