Academic literature on the topic 'Frequency refinement'

The static magnetic field and the alternating electric field were simultaneously imposed on AZ91D magnesium alloy melt, and α-dendrite particles were refined by the electromagnetic vibrations. The effect of the frequency of electromagnetic vibrations on microstructural refinement was quantitatively investigated. In the frequency range from 60 to 1000 Hz, the vibration frequency near 200 Hz was the most effective for the refinement of α-dendrite particles, and α-dendrite particles were refined up to approximately 100 μm from 1800 μm at this frequency. However, the effect of refinement by the electromagnetic vibrations became weak at frequencies above 400 Hz. Although the degree of refinement of the primary particles differed with the frequency of the electromagnetic vibrations, the dendrite arm spacing was almost constant, 30–40 μm, in our experiment. Therefore, the refinement of primary α-dendrite particles is likely to be caused by collapse of dendrite arms due to the cavitation phenomenon and the stirring of the melt.

Grain refinement is quite important for producing 7050 alloy ingot especially in large scale. Low frequency electromagnetic casting (LFEC) process was used to make 7050 aluminum alloy Φ310 ingots and study the effect of electromagnetic field and grain refiner on the microstructure of 7050 alloy ingots. The results showed that both grain refiner and low frequency electromagnetic field can result in some grain refinement of 7050 alloy. However, the low frequency electromagnetic field shows more remarkable grain refinement. For the grain refined alloy by grain refiner, further significant grain refinement can be achieved with the application of low frequency electromagnetic field. The finest microstructure was achieved by combining the applications of both grain refiner and electromagnetic field.

The refinement mechanism of pulsed magnetic field (PMF) was discussed by experimental investigation, and the effects of exciting frequency, exciting voltage, and delay time of PMF on grains refinement of superalloy were studied. The experimental results show that, as exciting frequency or exciting voltage is increased, the grains are refined. However, the grains become coarse when frequency increases further. As delay time of PMF increases, the grain size increases. The refinement effect of PMF is attributed to the detachment of heterogeneous nuclei on the mold wall and subsequently separation of nuclei in the melt. The Joule heat can prolong the continuous nucleation process. However, the refinement effect will be impaired if the Joule heat is strong enough to remelt the detached nuclei.

Abstract Considering the limitation of FFT frequency estimation method in resolution, this paper briefly introduces the complex modulation ZOOM-FFT and Chirp-Z transform spectrum zooming methods. The simulation results show that the ZOOM-FFT method has better anti spectrum leakage and interference effect. Furthermore, the two methods are applied to the frequency estimation of underwater high-speed maneuvering target, and it is found that Chirp-Z transform method can obtain smoother and stable frequency history, and has more flexible frequency resolution.

Purpose: To evaluate sound quality preferences of participants wearing hearing aids with different strengths of nonlinear frequency compression (NFC) processing versus no NFC processing. Two analysis methods, one without and one with a qualifier as to the magnitude of preferences, were compared for their percent agreement to differentiate a small difference in perceived sound quality as a result of applied NFC processing. Research Design: A single-blind design was used with participants unaware of the presence or strength of NFC processing (independent variable). The National Acoustic Laboratories-Nonlinear 2 (NAL-NL2) prescription of amplification was chosen because audibility is intentionally not prescribed in the presence of larger sensorineural hearing loss thresholds. A lack of prescribed audibility, when present, was deemed an objective qualifier for NFC. NFC is known to improve the input bandwidth available to listeners when high-frequency audibility is not otherwise available and increasing strengths of NFC were examined. Experimental condition 3 (EC3) was stronger than the manufacturer default (EC2). More aggressive strengths (e.g., EC4 and EC5), however, were expected to include excessive distortion and even reduce the output bandwidth that had been prescribed as audible by NAL-NL2 (EC1). Study Sample: A total of 14 male Veterans with severe high-frequency sensorineural hearing loss. Data Collection and Analysis: Participant sound quality preference ratings (dependent variable) without a qualifier as to the magnitude of preference were analyzed based on binomial probability theory, as is traditional with paired comparison data. The ratings with a qualifier as to the magnitude of preference were analyzed based on the nonparametric statistic of the Wilcoxon signed rank test. Results: The binomial probability analysis method identified a sound quality preference as well as the nonparametric probability test method. As the strength of NFC increased, more participants preferred the EC with less NFC. Fourteen of 14 participants showed equal preference between EC1 and EC2 perhaps, in part, because EC2 showed no objective improvement in audibility for six of the 14 participants (42%). Thirteen of the 14 participants showed no preference between NAL-NL2 and EC3, but all participants had an objective improvement in audibility. With more NFC than EC3, more and more participants preferred the other EC with less NFC in the paired comparison. Conclusions: By referencing the recommended sensation levels of amplitude compression (e.g., NAL-NL2) in the ear canal of hearing aid wearers, the targeting of NFC parameters can likely be optimized with respect to improvements in effective audibility that may contribute to speech recognition without adversely impacting sound quality. After targeting of NFC parameters, providers can facilitate decisions about the use of NFC parameters (strengths of processing) via sound quality preference judgments using paired comparisons.

La détermination de la forme d'un obstacle élastique immergé dans un milieu fluide à partir de mesures du champ d'onde diffracté est un problème d'un vif intérêt dans de nombreux domaines tels que le sonar, l'exploration géophysique et l'imagerie médicale. A cause de son caractère non-linéaire et mal posé, ce problème inverse de l'obstacle (IOP) est très difficile à résoudre, particulièrement d'un point de vue numérique. De plus, son étude requiert la compréhension de la théorie du problème de diffraction direct (DP) associé, et la maîtrise des méthodes de résolution correspondantes. Le travail accompli ici se rapporte à l'analyse mathématique et numérique du DP élasto-acoustique et de l'IOP. En particulier, nous avons développé un code de simulation numérique performant pour la propagation des ondes associée à ce type de milieux, basé sur une méthode de type DG qui emploie des éléments finis d'ordre supérieur et des éléments courbes à l'interface afin de mieux représenter l'interaction fluide-structure, et nous l'appliquons à la reconstruction d'objets par la mise en oeuvre d'une méthode de Newton régularisée.

This book seeks to understand how the need to respond to film has become a constituent feature in the ongoing development of the novel. It suggests that such fascination with film played out against the backdrop of a growing discourse about the novel's respectability. As the modern novel was increasingly venerated as a genre of aesthetic refinement and moral purpose, authors frequently turned their attention to film: a medium enviable not for the successes it achieved but for the lapses of taste it made obtrusive, and for the contradictions of address that it had the power to make attractive. In this impacted logic (and panic) of media transition, novelists came to credit narrative practices as yet undefined and unassimilated within literary tradition. In this, their texts respond to the felt devaluation of art in a transforming public culture which could seem at moments to be leaving the novel behind.

This chapter provides background on the discipline of epidemiology and its contribution to our understanding of childhood mental disorders. A summary is provided of data on the prevalence and correlates of mental disorders in children and adolescents in community surveys. Anxiety disorders are the most frequent conditions in children, followed by behavior disorders, mood disorders, and substance use disorders. About half of youth with one disorder also meet criteria for a second disorder, demonstrating the pervasive nature of comorbidity even in childhood. Less than half of youth with current mental disorders receive mental health specialty treatment. However, those with the most severe disorders tend to receive mental health services. Current issues that are now being identified in the field of child psychiatric epidemiology includes refinement of classification and assessment; integration of child and adult psychiatric epidemiology; and evaluation of both mental and medical disorders in children.

Synergetic Neural Network (SNN) as proposed by Hermann Haken is a novel top-down, self-organized system. In this chapter, its associated discrete SNN is proposed and the recognition stability and the convergence of a generalized discrete SNN is analyzed. We proposed an adaptive algorithm of iterative step length refinement for synergetic recognition, which can ensure fast convergence and network steadily for all kinds of input pattern. Additionally, we apply the SNN to trademark retrieval and study its ability to support affine invariant retrieval of 2D patterns. To this end, we propose an affine invariant input vector in the frequency domain for the SNN and evaluate the retrieval ability of such networks for different types of input queries, for example, query by complete trademark pattern and query by image components. We show experimentally that our proposed SNN method is noise tolerant as well as able to support affine invariant retrieval. This led us to propose a novel paradigm for trademark retrieval based on visual keywords whereby trademark images can be queried in terms of simple geometric components.

Pulse on time, pulse frequency, peak current, and base current are the important parameters to be optimized in pulsed current tungsten inert gas (PCTIG) welding of Al–SiC metal matrix composite. Experiments were designed and conducted using the L9 orthogonal array technique. The regression equation was developed using Design Expert® statistical software package to predict the weld center’s micro hardness, yield strength, ultimate strength, elongation (%), bending load, weld depth, weld width, cooling rate, and peak temperature near the weld zone of Al-8% SiC composite, welded using PCTIG welding. Correlation coefficient shows 0.9 for all the mechanical properties. This showed that the regression equation and the mathematical model developed were adequate. Analysis of contour plot, interaction effect, signal-to-noise ratio, and mean response were developed, the influence of each pulsed current parameter was evaluated at each level, and the percentage of influence was calculated by using pulsed current parameters. Ultimate tensile strength and bending load values depend on the microstructure. When the cooling rate is higher, fine microstructures are observed due to grain refinement; higher tensile strength and bending load are also observed. Due to the decreased cooling rate, coarse microstructures are observed, which result in poor tensile strength and bending load. PCTIG welding parameters are responsible for the change in the cooling rate of the weld zone. The optimization of the PCTIG welding parameters shows that the peak current and base current should be 160 and 60 A, respectively. Pulse on time is recommended to be 50%–55% and pulse frequency to be 5 Hz.

Abstract Darwin was the first to offer an evolutionary explanation for widespread sex differences in mating strategies across animal taxa. However, initial applications of evolutionary approaches to the study of human behavior were met with resistance. In response, social scientists began systematically applying rigorous evaluations of evolutionarily informed hypotheses by way of testable predictions. Mate choice research was a key area for this early work, focused on demonstrating sex differences in mating behavior. Subsequent research has tempered some earlier conclusions, increasingly relating mating strategies to aspects of socioecology. In particular, the adult sex ratio has emerged as an essential demographic variable contributing to behavioral variability within and between the sexes, leading to frequency-dependent rethinking for the patterning of mating competition and parental investment. Empirical examination of the association between adult sex ratio and aggression, family formation, partnership stability, and risk-taking is a growing field of research cross-cutting various literatures. In this chapter, we first describe early theory motivating research on sex differentiated behavior, followed by recent frequency-dependent reexaminations of sexual selection. Second, we introduce the adult sex ratio as a central determinant of fitness payoffs to differing reproductive strategies. Third, we review empirical studies on the consequences of sex ratio variation, highlighting outcomes related to sociosexuality, family formation, and violence. Fourth, we detail the maturation of the field, and where theoretical and empirical work has unveiled complexities regarding reproductive strategies. Finally, we reflect on future directions, where theoretical refinement is under way or needed, and highlight promising and novel research approaches.

In this chapter, we introduce a promising composite material, which can be used as a potential candidate in the field of charge storage, sensors, and spintronic devices. The structural, magnetic, and magnetodielectric properties of the pure cum composite samples are investigated. The Rietveld refinement of the X-ray data confirmed the presence of a single (A21am) and mixed phases (A21am + R-3c + Pbam) in the pure and composite sample, correspondingly. The SEM microstructure suggests the contrasting nature of the homogeneous and heterogeneous distribution of grains in the corresponding pure and composite sample. The magnetic properties of the composite sample increase due to the enhanced exchange interaction between the different magnetic ions. The frequency-dependent dielectric subjected to a constant magnetic field indicates the signature of magnetodielectric (MD) coupling for both the samples. The field variation of the MD loop shows the symmetric hysteresis loop in the composite due to the addition of magnetostrictive La0.67Sr0.33MnO3 and the non-collinear antiferromagnetic Bi2Fe4O9 phase. The maximum value of MD% (~0.12%) is enhanced by ~13 times in the composite than in the pure sample. Therefore, the improved MD coupling and symmetric switching of the MD loop of the composite make it a suitable candidate for low power consumption storage devices.

A systematic literature review of published sources that discuss radio frequency identification technology, ubiquitous health care, and dosage measurement was performed. The results were then critiqued. Methods of storing data and using Radio Frequency Identification (RFID) were studied. These results were used as an aid for developing a prototype system for monitoring medication dosages in a home health care environment. The combination of an RFID technology – the Intel Wireless Sensor Platform (WISPs) and the construction of a specific pill dispensing container in this prototype demonstrated that it is possible to use RFID technology to effectively and ubiquitously monitor and track drug taking compliance. With further refinements on the dispensing unit and optimization of the software this product could be manufactured and released to home care patients to help increase compliance and reduce health related issues. This could form the heart of a modular telecare data collection system. RFID-based devices that can store data in standardized formats may allow incremental development of home telecare systems in an economical fashion.

Inhomogeneous optical coatings have received a lot of attention in recent years. Not only do they have unique physical properties, but they have also been found useful as an intermediate stage in the design of conventional multilayers.

Background Lung cancer is the number one cause of cancer death worldwide.(1) It is the fifth most commonly diagnosed cancer in Australia (12,741 cases diagnosed in 2018) and the leading cause of cancer death.(2) The number of years of potential life lost to lung cancer in Australia is estimated to be 58,450, similar to that of colorectal and breast cancer combined.(3) While tobacco control strategies are most effective for disease prevention in the general population, early detection via low dose computed tomography (LDCT) screening in high-risk populations is a viable option for detecting asymptomatic disease in current (13%) and former (24%) Australian smokers.(4) The purpose of this Evidence Check review is to identify and analyse existing and emerging evidence for LDCT lung cancer screening in high-risk individuals to guide future program and policy planning. Evidence Check questions This review aimed to address the following questions: 1. What is the evidence for the effectiveness of lung cancer screening for higher-risk individuals? 2. What is the evidence of potential harms from lung cancer screening for higher-risk individuals? 3. What are the main components of recent major lung cancer screening programs or trials? 4. What is the cost-effectiveness of lung cancer screening programs (include studies of cost–utility)? Summary of methods The authors searched the peer-reviewed literature across three databases (MEDLINE, PsycINFO and Embase) for existing systematic reviews and original studies published between 1 January 2009 and 8 August 2019. Fifteen systematic reviews (of which 8 were contemporary) and 64 original publications met the inclusion criteria set across the four questions. Key findings Question 1: What is the evidence for the effectiveness of lung cancer screening for higher-risk individuals? There is sufficient evidence from systematic reviews and meta-analyses of combined (pooled) data from screening trials (of high-risk individuals) to indicate that LDCT examination is clinically effective in reducing lung cancer mortality. In 2011, the landmark National Lung Cancer Screening Trial (NLST, a large-scale randomised controlled trial [RCT] conducted in the US) reported a 20% (95% CI 6.8% – 26.7%; P=0.004) relative reduction in mortality among long-term heavy smokers over three rounds of annual screening. High-risk eligibility criteria was defined as people aged 55–74 years with a smoking history of ≥30 pack-years (years in which a smoker has consumed 20-plus cigarettes each day) and, for former smokers, ≥30 pack-years and have quit within the past 15 years.(5) All-cause mortality was reduced by 6.7% (95% CI, 1.2% – 13.6%; P=0.02). Initial data from the second landmark RCT, the NEderlands-Leuvens Longkanker Screenings ONderzoek (known as the NELSON trial), have found an even greater reduction of 26% (95% CI, 9% – 41%) in lung cancer mortality, with full trial results yet to be published.(6, 7) Pooled analyses, including several smaller-scale European LDCT screening trials insufficiently powered in their own right, collectively demonstrate a statistically significant reduction in lung cancer mortality (RR 0.82, 95% CI 0.73–0.91).(8) Despite the reduction in all-cause mortality found in the NLST, pooled analyses of seven trials found no statistically significant difference in all-cause mortality (RR 0.95, 95% CI 0.90–1.00).(8) However, cancer-specific mortality is currently the most relevant outcome in cancer screening trials. These seven trials demonstrated a significantly greater proportion of early stage cancers in LDCT groups compared with controls (RR 2.08, 95% CI 1.43–3.03). Thus, when considering results across mortality outcomes and early stage cancers diagnosed, LDCT screening is considered to be clinically effective. Question 2: What is the evidence of potential harms from lung cancer screening for higher-risk individuals? The harms of LDCT lung cancer screening include false positive tests and the consequences of unnecessary invasive follow-up procedures for conditions that are eventually diagnosed as benign. While LDCT screening leads to an increased frequency of invasive procedures, it does not result in greater mortality soon after an invasive procedure (in trial settings when compared with the control arm).(8) Overdiagnosis, exposure to radiation, psychological distress and an impact on quality of life are other known harms. Systematic review evidence indicates the benefits of LDCT screening are likely to outweigh the harms. The potential harms are likely to be reduced as refinements are made to LDCT screening protocols through: i) the application of risk predication models (e.g. the PLCOm2012), which enable a more accurate selection of the high-risk population through the use of specific criteria (beyond age and smoking history); ii) the use of nodule management algorithms (e.g. Lung-RADS, PanCan), which assist in the diagnostic evaluation of screen-detected nodules and cancers (e.g. more precise volumetric assessment of nodules); and, iii) more judicious selection of patients for invasive procedures. Recent evidence suggests a positive LDCT result may transiently increase psychological distress but does not have long-term adverse effects on psychological distress or health-related quality of life (HRQoL). With regards to smoking cessation, there is no evidence to suggest screening participation invokes a false sense of assurance in smokers, nor a reduction in motivation to quit. The NELSON and Danish trials found no difference in smoking cessation rates between LDCT screening and control groups. Higher net cessation rates, compared with general population, suggest those who participate in screening trials may already be motivated to quit. Question 3: What are the main components of recent major lung cancer screening programs or trials? There are no systematic reviews that capture the main components of recent major lung cancer screening trials and programs. We extracted evidence from original studies and clinical guidance documents and organised this into key groups to form a concise set of components for potential implementation of a national lung cancer screening program in Australia: 1. Identifying the high-risk population: recruitment, eligibility, selection and referral 2. Educating the public, people at high risk and healthcare providers; this includes creating awareness of lung cancer, the benefits and harms of LDCT screening, and shared decision-making 3. Components necessary for health services to deliver a screening program: a. Planning phase: e.g. human resources to coordinate the program, electronic data systems that integrate medical records information and link to an established national registry b. Implementation phase: e.g. human and technological resources required to conduct LDCT examinations, interpretation of reports and communication of results to participants c. Monitoring and evaluation phase: e.g. monitoring outcomes across patients, radiological reporting, compliance with established standards and a quality assurance program 4. Data reporting and research, e.g. audit and feedback to multidisciplinary teams, reporting outcomes to enhance international research into LDCT screening 5. Incorporation of smoking cessation interventions, e.g. specific programs designed for LDCT screening or referral to existing community or hospital-based services that deliver cessation interventions. Most original studies are single-institution evaluations that contain descriptive data about the processes required to establish and implement a high-risk population-based screening program. Across all studies there is a consistent message as to the challenges and complexities of establishing LDCT screening programs to attract people at high risk who will receive the greatest benefits from participation. With regards to smoking cessation, evidence from one systematic review indicates the optimal strategy for incorporating smoking cessation interventions into a LDCT screening program is unclear. There is widespread agreement that LDCT screening attendance presents a ‘teachable moment’ for cessation advice, especially among those people who receive a positive scan result. Smoking cessation is an area of significant research investment; for instance, eight US-based clinical trials are now underway that aim to address how best to design and deliver cessation programs within large-scale LDCT screening programs.(9) Question 4: What is the cost-effectiveness of lung cancer screening programs (include studies of cost–utility)? Assessing the value or cost-effectiveness of LDCT screening involves a complex interplay of factors including data on effectiveness and costs, and institutional context. A key input is data about the effectiveness of potential and current screening programs with respect to case detection, and the likely outcomes of treating those cases sooner (in the presence of LDCT screening) as opposed to later (in the absence of LDCT screening). Evidence about the cost-effectiveness of LDCT screening programs has been summarised in two systematic reviews. We identified a further 13 studies—five modelling studies, one discrete choice experiment and seven articles—that used a variety of methods to assess cost-effectiveness. Three modelling studies indicated LDCT screening was cost-effective in the settings of the US and Europe. Two studies—one from Australia and one from New Zealand—reported LDCT screening would not be cost-effective using NLST-like protocols. We anticipate that, following the full publication of the NELSON trial, cost-effectiveness studies will likely be updated with new data that reduce uncertainty about factors that influence modelling outcomes, including the findings of indeterminate nodules. Gaps in the evidence There is a large and accessible body of evidence as to the effectiveness (Q1) and harms (Q2) of LDCT screening for lung cancer. Nevertheless, there are significant gaps in the evidence about the program components that are required to implement an effective LDCT screening program (Q3). Questions about LDCT screening acceptability and feasibility were not explicitly included in the scope. However, as the evidence is based primarily on US programs and UK pilot studies, the relevance to the local setting requires careful consideration. The Queensland Lung Cancer Screening Study provides feasibility data about clinical aspects of LDCT screening but little about program design. The International Lung Screening Trial is still in the recruitment phase and findings are not yet available for inclusion in this Evidence Check. The Australian Population Based Screening Framework was developed to “inform decision-makers on the key issues to be considered when assessing potential screening programs in Australia”.(10) As the Framework is specific to population-based, rather than high-risk, screening programs, there is a lack of clarity about transferability of criteria. However, the Framework criteria do stipulate that a screening program must be acceptable to “important subgroups such as target participants who are from culturally and linguistically diverse backgrounds, Aboriginal and Torres Strait Islander people, people from disadvantaged groups and people with a disability”.(10) An extensive search of the literature highlighted that there is very little information about the acceptability of LDCT screening to these population groups in Australia. Yet they are part of the high-risk population.(10) There are also considerable gaps in the evidence about the cost-effectiveness of LDCT screening in different settings, including Australia. The evidence base in this area is rapidly evolving and is likely to include new data from the NELSON trial and incorporate data about the costs of targeted- and immuno-therapies as these treatments become more widely available in Australia.