Modal Strength Research Articles

Model Analysis and Optimization Design for Mg-Based Instrument Panel Beam Assembly

Based on the basic structure in the practical installation condition, the static model of the instrument panel (IP) beam assembly is developed. To reduce the weight, Mg is substituted for steel as the material of the structure. The finite element software is used to evaluate the constraint modal performance, rigidness and strength withstanding the specific load. After the comparison of model analysis with different materials, the Mg-based IP beam assembly is optimized to achieve the performance the steel-based one has. The process offers the reference to the lightweight design of Mg-based IP beam assembly.

Biomedical Imaging Instrumentation and Design in Neurological Disorder Data Acquisition

The recent introduction of high-resolution molecular imaging technology is considered by many experts as a major breakthrough that will potentially lead to a revolutionary paradigm shift in health care and revolutionize clinical practice. This paper explores the challenges and strengths of the current major imaging modalities, as well as the biophysics engineering their repertoire of capabilities. Advancements in the mechanical aspects of both PET and SPECT imaging will advance molecular imaging diagnostic capabilities and have a direct impact on clinical medicine and biomedical research practice. A better understanding of the strengths and limitations of functional imaging modalities in the context of their particular hardware and software mechanics will shed light onto how we can advance their diagnostic capabilities on a biological level. Herein, this paper demonstrates the fundamental biomechanical differences between PET and SPECT imaging, and how these fundamental differences translate into clinically relevant data acquisition for brain disorders.

Finite Element Dynamics Analysis of Vibrating Feeder

According to actual geometry size of vibrating feeder, the finite element calculating model for vibrating feeder box is established in this paper. ANSYS software is used to perform modal analysis and dynamic strength analysis for the vibration feeder box, and the former ten modal frequencies of the sieving box and dynamic stress of the sieving box whole is obtained, which provides a theoretical basis for strength design of the vibrating feeder.

A New Method Based on Finite Element Analysis for Crankshaft Strength

This paper presents a new method for the analysis of the crankshaft strength by using the softwares of solidworks, matlab and ansys. Using the powerful modeling function of solidworks, the three-dimensional model of crankshaft was established. Applying the techniques of numerical operation, graph display and GUI of matlab, the simulation calculations of kinematics, dynamics of crankshaft was carried out and the force and torque of crankshaft was obtained. Making full use of finite element analysis function of ansys, the modal analysis and strength analysis of crankshaft were made. The results show that it is valid to take the respective advantages of solidworks, matlab and ansys to establish a simple and effective approach for the analysis of the crankshaft strength, which supplies foundation for the optimization design and dynamic response of crankshaft.

A displacement-based seismic design method with damage control for RC buildings

This paper presents a displacement-based seismic design method with damage control, in which the targets for the considered performance level are set as displacements and a damage distribution is proposed by the designer. The method is based on concepts of basic structural dynamics and of a reference single degree of freedom system associated to the fundamental mode with a bilinear behaviour. Based on the characteristics of this behaviour curve and on the requirements of modal spectral analysis, the stiffness and strength of the structural elements of the structure satisfying the target design displacement are calculated. The formulation of this method is presented together with the formulations of two other existing methods currently considered of practical interest. To illustrate the application of the proposed method, 5 reinforced concrete plane frames: 8, 17 and 25 storey regular, and 8 and 12 storey irregular in elevation. All frames are designed for a seismic demand defined by single earthquake record in order to compare the performances and damage distributions used as design targets with the corresponding results of the nonlinear step by step analyses of the designed structures subjected to the same seismic demand. The performances and damage distributions calculated with these analyses show a good agreement with those postulated as targets.

Offline fusion of co-registered intravascular ultrasound and frequency domain optical coherence tomography images for the analysis of human atherosclerotic plaques

To demonstrate the feasibility and potential usefulness of an offline fusion of matched optical coherence tomography (OCT) and intravascular ultrasound (IVUS)/virtual histology (IVUS-VH) images. A total of nine matched OCT, IVUS, and IVUS-VH cross-sections were fused according to a methodology described in this report. On the basis of the fused images, an OCT-IVUS-VH tissue classification algorithm is proposed taking into account the individual strength of both techniques. Offline fusion of co-registered IVUS and OCT is feasible and combines the strengths of both imaging modalities, potentially improving the diagnostic accuracy of plaque characterisation.

When the doctor needs an engineer to be the matchmaker

When the doctor needs an engineer to be the matchmaker

Exploiting multiple sensor modalities for classification of underwater munitions: A Dempster–Shafer theoretic approach

Detection and classification of underwater UXOs (UneXploded Ordnance) is a task that is receiving considerable attention from the DoD and related agencies that are involved in management of military munitions. Achieving a reasonable accuracy in detection and classification of these objects is extremely difficult mainly due to the harsh cluttered underwater environment. It is now an accepted fact that no single sensing technology can be both accurate and cost-effective. Low visibility in underwater exposes a significant limitation to optical cameras which are usually better suited for identifying the physical shape of objects. While acoustic imaging is a good alternative, the characteristics of imaging and physical system artifacts make the object recognition task non-trivial. Multi-sensory fusion provides an avenue to exploit the strengths of individual sensors and modalities while mitigating their weaknesses. We address the problem of fusion of multiple sensory information for the task of underwater UXO detection via the use of a Dempster–Shafer (DS) theoretic evidence fusion scheme. The DS theoretic foundation of our fusion algorithm also enables it to incorporate domain expert opinions and knowledge from databases to assist in the detection and classification tasks. We illustrate this method via the use of real data obtained at a test site located in the Florida Atlantic University premises.

Development and Application of a Multimodal Contrast Agent for SPECT/CT Hybrid Imaging

Hybrid or multimodality imaging is often applied in order to take advantage of the unique and complementary strengths of individual imaging modalities. This hybrid noninvasive imaging approach can provide critical information about anatomical structure in combination with physiological function or targeted molecular signals. While recent advances in software image fusion techniques and hybrid imaging systems have enabled efficient multimodal imaging, accessing the full potential of this technique requires development of a new toolbox of multimodal contrast agents that enhance the imaging process. Toward that goal, we report the development of a hybrid probe for both single photon emission computed tomography (SPECT) and X-ray computed tomography (CT) imaging that facilitates high-sensitivity SPECT and high spatial resolution CT imaging. In this work, we report the synthesis and evaluation of a novel intravascular, multimodal dendrimer-based contrast agent for use in preclinical SPECT/CT hybrid imaging systems. This multimodal agent offers a long intravascular residence time (t(1/2) = 43 min) and sufficient contrast-to-noise for effective serial intravascular and blood pool imaging with both SPECT and CT. The colocalization of the dendritic nuclear and X-ray contrasts offers the potential to facilitate image analysis and quantification by enabling correction for SPECT attenuation and partial volume errors at specified times with the higher resolution anatomic information provided by the circulating CT contrast. This may allow absolute quantification of intramyocardial blood volume and blood flow and may enable the ability to visualize active molecular targeting following clearance from the blood.

The role of repair in modulating modal stances in Chinese discourse

This study explores the intersubjective and dynamic construction of modal meanings in Chinese discourse. Specifically, it examines the role conversational repair plays in ascertaining the entailments of modal meanings such as obligation, possibility and permissibility, specifying the range of modal strengths, and assigning an emergent and negotiated quality to these meanings. It argues that repair shapes and sharpens speakers’ modal stances, especially when the modal expression is polysemous. Illustrative data are drawn from 30 hours of audio/video recorded interaction in weekend Chinese language schools.

Modal strength reduction factors for seismic design of plane steel frames

A new method for the seismic design of plane steel moment resisting frames is developed. This method determines the design base shear of a plane steel frame through modal synthesis and spectrum analysis utilizing different values of the strength reduction (behavior) factor for the modes considered instead of a single common value of that factor for all these modes as it is the case with current seismic codes. The values of these modal strength reduction factors are derived with the aid of a) design equations that provide equivalent linear modal damping ratios for steel moment resisting frames as functions of period, allowable interstorey drift and damage levels and b) the damping reduction factor that modifies elastic acceleration spectra for high levels of damping. Thus, a new performance-based design method is established. The direct dependence of the modal strength reduction factor on desired interstorey drift and damage levels permits the control of deformations without their determination and secures that deformations will not exceed these levels. By means of certain seismic design examples presented herein, it is demonstrated that the use of different values for the strength reduction factor per mode instead of a single common value for all modes, leads to more accurate results in a more rational way than the codebased ones.

Optical probes and the applications in multimodality imaging

Optical imaging essentially refers to in vivo fluorescence imaging and bioluminescence imaging. These types of imaging are widely used visualization methods in biomedical research and are important in molecular imaging. A new generation of imaging agents called multimodal probes have emerged in the past few years. These probes can be detected by two or more imaging modalities, which harnesses the strengths of the different modalities and enables researchers to obtain more information than can be achieved using only one modality. Owing to its low cost and the large number of probes available, the optical method plays an important role in multimodality imaging. In this mini-review, we describe the available multimodal imaging probes for in vivo imaging that combine optical imaging with other modalities.

Closed‐bore XMR (CBXMR) systems for aortic valve replacement: X‐ray tube imaging performance

A hybrid closed-bore x-ray/MRI system (CBXMR) is proposed to improve the safety and efficacy of percutaneous aortic valve replacement procedures. In this system, an x-ray C-arm will be positioned about 1 m from the entrance of a 1.5 T MRI scanner. The CBXMR system will harness the complementary strengths of both modalities to guide and deploy a bioprosthetic valve into the aortic annulus of the heart without coronary artery obstruction. A major challenge in constructing this system is ensuring proper operation of a rotating-anode x-ray tube in the MRI magnetic fringe field environment. The electron beam in the x-ray tube responsible for producing x rays can be deflected by the fringe field. However, the clinical impact of electron beam deflection in a magnetic field has not yet been studied. Here, the authors investigated changes in focal spot resolving power, field of view shift, and field of view truncation in x-ray images as a result of electron beam deflection. The authors found that in the fringe field acting on the x-ray tube at the clinical location for the x-ray C-arm (4 mT), focal spot size increased by only 2%, so the fringe field did not limit the resolving power of the x-ray system. The magnetic field also caused the field of view to shift by 3 mm. This shift must be corrected to avoid unnecessary primary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. The fringe field was too weak to cause field of view truncation.

Web-Based Education in Graduate Nursing Programs

Distance education is increasingly prevalent in nursing programs, with a recent emphasis on graduate programs. This article reviews the strengths of alternative teaching modalities, including reaching those students who might not otherwise be able to further their studies. Innovative teaching strategies using the technology strengthen a student’s ability to acquire information and utilize evidence-based practice, similar to what will be faced in the nurse practitioner (NP) role. We will also examine faculty perspectives to see how to best proceed with distance education.

Closed bore XMR (CBXMR) systems for aortic valve replacement: investigation of rotating-anode x-ray tube heat loadability.

In order to improve the safety and efficacy of percutaneous aortic valve replacement procedures, a closed bore hybrid x-ray/MRI (CBXMR) system is proposed in which an x-ray C-arm will be positioned with its isocenter approximately =1 m from the entrance of a clinical MRI scanner. This system will harness the complementary strengths of both modalities to improve clinical outcome. A key component of the CBXMR system will be a rotating anode x-ray tube to produce high-quality x-ray images. There are challenges in positioning an x-ray tube in the magnetic fringe field of the MRI magnet. Here, the effects of an external magnetic field on x-ray tube induction motors of radiography x-ray tubes and the corresponding reduction of x-ray tube heat loadability are investigated. Anode rotation frequency f(aode) was unaffected when the external magnetic field Bb was parallel to the axis of rotation of the anode but decreased when Bb was perpendicular to the axis of rotation. The experimental f(anode) values agreed with predicted values to within +/-3% over a Bb range of 0-30 mT. The MRI fringe field at the proposed location of the x-ray tube mounted on the C-arm (approximately =4 mT) reduced f(anode) by only 1%, so x-ray tube heat loadability will not be compromised when using CBXMR systems for percutaneous aortic valve replacement procedures. Eddy current heating power in the rotor due to an MRI fringe field was found to be two orders of magnitude weaker than the heating power produced on the anode due to a fluoroscopic exposure, so eddy current heating had no effect on x-ray tube heat loadability.

Strength of modes in rotating machinery

A new method for the analysis of modal strength of the rotor systems with periodically time-varying parameters due to the presence of either rotating or stationary asymmetry is proposed. The method is based on the complete development of the modal analysis by introducing the modulated coordinates to derive the equivalent infinite-order time-invariant Hill's matrix equation from the finite-order time-varying matrix equation. Depending upon the level of possible contribution of each mode to forced response, the modal strength of a mode is rigorously derived from the norm order analysis of the associated eigenvector; thereby, the modes are classified as strong or weak modes. It is shown that the directional frequency response functions are useful in identifying the strength of modes in detail, or equivalently, the modes of symmetry, anisotropy, asymmetry and coupled asymmetry. Two illustrative examples with a simple, yet general, analysis rotor model and a practical flexible asymmetric rotor finite element (FE) model with an open transverse crack are treated to demonstrate the theoretical findings and effectiveness of the proposed method.

Progress in Multimodality Imaging: Truly Simultaneous Ultrasound and Magnetic Resonance Imaging

Multimodality medical imaging takes advantage of the strengths of different imaging modalities to provide a more complete picture of the anatomy under investigation. Many complementary modalities have been combined to form such systems and some are gaining use clinically. One combination that has not been developed, in large part due to technical difficulties, is a combined magnetic resonance (MR) and ultrasound (US) imaging system. Such a system offers the potential to combine the strengths of these modalities in a wide range of diagnostic and therapeutic applications. The goal of this study was to evaluate the feasibility of performing simultaneous multimodality US and MR imaging. An US imaging system capable of operation in a clinical MR imager was developed, and methods to perform simultaneous imaging were investigated. Simultaneous imaging was feasible without any mutual interference by either filtering the transmitted and received US signal, or by synchronizing data acquisition between the two imaging systems. Spatial registration between the two modalities was achieved by using a reference phantom with implanted glass beads in orthogonal planes. Excellent agreement was observed between spatial measurements of an object made with both modalities, and the feasibility of using this system in vivo was demonstrated in a rabbit model. Simultaneous US and MR imaging is achievable, and can provide complementary information about an object under investigation. This demonstration of technical feasibility and the development of a prototype system open up the potential to investigate the promising clinical applications of this combined technology.

Static and dynamic characteristics of VCSELs with polarisation-selective optical feedback

Static and dynamic characteristics of birefringent vertical-cavity surface-emitting lasers (VCSELs) subject to both isotropic and polarisation-selective optical feedback are investigated theoretically. The model considers two orthogonally polarised transverse modes; moreover, the spatial dependences of photon density, carrier density and injection current are taken into account. For a short external cavity, the two-mode VCSELs can be forced to operate with one mode by introducing the polarisation-selective optical feedback. It is further shown that the phase of feedback light determined by the external cavity length affects the laser operation characteristics greatly, that is, when the external cavity length is chosen, the reflected light strengthens (weakens) the optical field in the laser cavity, the mode that has the same polarisation direction can be enhanced (suppressed), while the other mode is suppressed (enhanced) correspondingly. For a relatively long external cavity, the continuous wave operation of VCSELs is destabilised and rich non-linear dynamics are excited. By increasing the external cavity length, the VCSELs follow a period-halving route to chaos. It is also found that the evolution of dynamics shows periodic repetition with respect to the external cavity length, and the period is half of the lasing wavelength. Further investigation shows that, for isotropic feedback, both modes exhibit the same dynamics and similar mode intensity; for polarisation-selective feedback, though similar non-linear behaviours are observed, the modal strengths are quite different, that is, the feedback light enhances one mode while greatly suppressing the orthogonally polarised mode.

Scalar quantity implicatures and the interpretation of modality: Problems in the deontic domain

This paper argues that scalar quantity implicatures do not work across the modal domain as a whole, as has traditionally been assumed in the literature, but that deontic modal expressions pose a specific problem for the mechanism of scalar implicatures. It is argued that the problems with deontic modality are due to the fact that expressions of permission and obligation are different on two dimensions: they do not just express weaker and stronger commitment to desirability on the part of some authority, but they also carry different presuppositions about the willingness of the modal agent (the person who is allowed or obliged to do something) to carry out the action in question. The consequence of this difference is that the two types, unlike their epistemic counterparts, do not form a perfect scale. They differ in more respects than just modal strength, and this disrupts the implicature mechanism that works well for the weaker and stronger degrees of epistemic modality.

Controversies in emergency radiology. CT versus ultrasound in the evaluation of blunt abdominal trauma.

There has been controversy regarding ultrasonography (US) versus CT in blunt abdominal trauma (BAT). Each modality has its strengths and weaknesses. US is fast and allows resuscitative efforts to proceed while the patient is being scanned. However, the sensitivity of US is inferior to that of CT, and there is user variability. CT is better at determining the extent, type, and grade of injury, resulting in a more tailored therapeutic plan and safe conservative management of many patients. However, CT involves ionizing radiation, cannot be performed portably, and requires only visual monitoring while scanning. Given each modality's strengths and weaknesses we conclude that CT is the preferred examination when the BAT patient is stable or moderately stable, enough to be taken to CT. If a BAT patient is unstable, US is beneficial in screening for certain injuries or large hemoperitoneum prior to an exploratory laparotomy.