A modal approach towards substitutions

Recent developments of the modal-based aeroelastic optimization approach facilitated efficient treatment of static-aeroelastic and stress constraints. The reduced-size models use low-frequency normal modes of the baseline structure as fixed generalized coordinates throughout the optimization process. The modal approach is extended to allow the expansion of the modal basis by the addition of static modes generated in previous design steps. Being based on modal perturbations stored in the modal data base before the optimization process starts, the basis expansion accelerates the convergences to the optimal design. Numerical examples with realistic fighter- aircraft models demonstrate practical applications with CPU speed-up factors of ~10, compared with the regular discrete-coordinate approach, with negligible loss of accuracy. HE desire for efficient procedures for optimal design of com- plex structures motivated the development of reduced-size op- timization schemes in which calculations of stability and response parameters and their sensitivity to changes in the design variables are based on a set of low-frequency vibration modes of a base- line structure. The modal approach is especially attractive in multi- disciplinary cases in which the excitation loads are affected by the structural response, such as in aeroelastic and control-augmented systems. The ASTROS code1 was developed to provide a multidisciplinary analysis and design capability for aerospace structures. The con- sidered disciplines include structural analysis, aeroelastic analysis, and some features of the interaction with the control system. As in other commonly used analysis and optimization schemes,24 the dynamic response and the stability features are treated by the modal approach, but the static-aeroelastic and stress disciplines are treated by the discrete approach. The use of modal coordinates in static-aeroelastic analysis was shown in Ref. 5 to be extremely efficient and of good accuracy in application to realistic aircraft models. Structural optimization with static-aeroelastic constraints was later performed with the base- line normal modes serving as a fixed set of generalized coordinates throughout the entire optimization run.6 The fixed-modal-basis ap- proach was shown in Ref. 6 to be of good accuracy with design variable changes of less than ~20%. Larger changes required the update of the full finite-element model such that the optimization process could be resumed with new modal coordinates. Even when the modal approach was successfully applied in multidisciplinary optimization with static- and dynamic-aeroelastic constraints,7 it was not ready yet for application to stress constraints. The main reason for not using the modal approach for stresses was that it might yield erroneous results in cases of concentrated loads and in cases of local structural changes. Recent developments of the

Ethmoid Sinus Cancer: Experience and Oncological Outcomes at Memorial Sloan-Kettering Cancer Center (MSKCC): Non-Squamous Cell Malignancies of the Head and Neck (thyroid, skin cancers, salivary gland and sinus cancers)

A general modal approach for the development of optimal multi-layer stacked vibration energy harvesters

The current state of wisdom in predicting electromagnetically-induced stator vibration and noise considers oscillatory radial forces acting in the airgap at the tips of stator teeth. The same oscillations in magnetic flux density which cause these forces also cause internal stresses in the magnetic iron and there is not a consensus as to the relative importance of these. This paper presents a method by which the importance of magnetostriction as a vibration-induction mechanism can be quantified.

Singular perturbation techniques for order reduction are based on decomposing the high-order system into two parts. Approximation of the high-order system dynamics by the low-order model is mainly dependent on this partition. This paper introduces a measure for the degree of dependence of the state variables on the high-order dominant eigenvalues. By means of this measure it is not only possible to find an appropriate decomposition yielding a good low-order model, but also to get an indication of the order of the reduced model. Two illustrative examples demonstrate the main results.

A modal approach for the development of optimal configurations of two-layer piezoelectric vibration energy harvesters is presented. The harvester comprises a primary cantilevered beam to which a secondary beam is attached via a mass that is located along the length of the primary beam. An additional mass is located along the secondary beam. The two masses are used to tune the natural frequencies of the composite system and one of them also serves as a spacer between the two beams. By varying the dimensions of the beams and masses, and the locations of the masses along the beams, the harvester can produce close resonance frequencies and significant power output. Thus, the frequency bandwidth of significant power generation by the harvester can be extended. To judge the performance of any harvester configuration requires a full analysis, using the coupled electromechanical equations of the piezoelectric harvester, to determine the electrical power output. However, the analysis is lengthy and time consuming. To hasten the process, a modal approach has been developed. The approach determines the modal performance by means of the mass ratio (which represents the influence of modal mechanical behaviour on the power density directly) and the modal electromechanical coupling coefficient. The modal parameters required by the approach are computed numerically by finite element analysis. The modal approach is used to select harvester configurations with optimal or near-optimal performance, which are harvester configurations with close resonances and moderate values of mass ratio. A full analysis is subsequently performed to determine the power outputs of these harvester configurations.

An analytical framework, based on the refinements to the mobility and modal approaches, is proposed to calculate the structural power flow through multidimensional compliant joints or connections. The built-up assembly is divided into the classical model of a noise control problem, i.e., source, path (joint), and receiver. Both methods place emphasis on the joint properties and account for different paths and mechanisms of noise transmission (e.g., forces and moments). Only the discrete system formulation is considered and results obtained via exact (unsynthesized) and the proposed component synthesis procedures perfectly match with each other. The mobility method is found to be useful for distinguishing which path (joint) transmits power and the complementary modal method yields information on the newly defined modal dissipation efficiencies. Finally the issues of scalar versus vector joints and rigid versus compliant connections are addressed by using a pedagogical example of a 10 degrees-of-freedom system.

Sound Insulation of Building Elements at Low Frequency: A Modal Approach

Background:Historically, gambling has been viewed as a sin and later as a vice. More recently, disordered gambling has been seen as an illness determined by genetic and environmental factors and individual decision making. only 10-20% of pathological gamblers actually seek professional help. Our case is unique, as unlike most pathological gamblers, our patient actively sought treatment and showed good response in early follow-up period.Case report:A 37 years old male, with family history of problem gambling and substance use in father, premorbid narcissistic traits, came to psychiatric OPD with complaints of depressive symptoms for 4 months, in the background of progressively increasing engagement in online gambling with consequent heavy financial loss over the past 7 years. According to DSM-V diagnosed with gambling disorder, he was treated with tab fluoxetine 20 mg, naltrexone 50 mg and psychoanalytically oriented therapy.Discussion:A comprehensive treatment plan that incorporates a multi- modal approach should be used in managing pathological gamblers with pharmacological and psychoanalytically oriented therapy has shown good and early response in our patient.

This article discusses the acoustic scattering in a waveguide containing flexible cavity bridged by vertical membranes. A tailored-Galerkin approach is adopted for the solution of governing boundary value problem. Unlike to the usual Mode-Matching (MM) technique, the schemes adopted here for solution modify the MM procedure by using Galerkin and Modal approaches. In Galerkin process, the displacement of vertical membrane is expanded by means of the usual orthogonal modes whilst in the later case, this displacement is found by utilizing the non-orthogonal modes of wave-bearing cavity. The results for scattering powers and transmission loss are shown against frequency and the dimensions of the chamber. A good agreement in results obtained via Galerkin and Modal approaches for different sets of edge conditions is seen. The numerical results show that the choices of edge conditions significantly affect the transmission loss and scattering powers.

Quadrotors are making a difference to numerous civilian and military applications. There are various approaches to realize formation flight control. In this paper, a comparison between sliding mode and second-order consensus approaches for quadrotor leader-follower formation flight was conducted. Sliding mode and second-order consensus algorithms were employed to design the formation controller for steady formation flight. Both leader and the follower quadrotors are controlled by proportional integral derivative controllers. The leader follows the desired trajectory while the followers follow the instruction calculated by the formation controller. Simulations are carried out to analyze the effect of these two approaches. The result indicates that the followers can follow the leader's trajectory and keep the formation fairy well under the control of both approaches. However, the sliding mode approach can achieve faster position convergence effect, while the second-order consistency approach has better disturbance suppression performance in case of disturbance.

Analysis of the hydrodynamic damping of a hydrofoil with leading edge cavitation using the modal work approach

Random-vibration fatigue evaluation can be of considerable importance in the design phase of aerospace structures due to the severe dynamic loads in service. This paper presents the utilization of modal stress approach to the issue of structural random-vibration fatigue evaluation. Prognosis of random fatigue hotspots by using stress mode shapes is theoretically demonstrated. A two-step procedure is proposed for computational efficiency. Firstly, modal stress analysis is conducted to locate the fatigue hotspots in a dynamic structure. Secondly, the frequency domain-based approach for random fatigue evaluation is performed at these hotspots, as opposed to the computation of the entire structure as before. The capability of stress mode shapes to locate fatigue hotspots is verified by numerical investigations. The finite element model of a single-lap plate structure containing various opening holes was constructed for case study. Six elements were identified as hotspots by using modal stress distributions. Then, random responses and fatigue evaluation of the entire structure were carried out for verification. Good agreement was observed between the fatigue damage contour and the modal stress distributions, which can indicate that the critical positions predicted by stress mode shapes have good accuracy. The calculation time and storage space can be significantly reduced by means of the proposed evaluation procedure. Therefore, the accuracy and efficiency of utilization of modal stress approach in random fatigue evaluation can be ensured.

IntroductionDiabetic foot ulcer (DFU) with osteomyelitis is the devastating condition, which is a challenge to surgeons in saving the limb of the patient and in many circumstances ends up with amputation, which leaves physical and psychosocial trauma for both the patient and patient's family. Presentation of caseA 48-year-old female patient with uncontrolled type 2 diabetes presented with swelling and gangrenous deep circular ulcer of size approx. 3 × 4 cm on plantar aspect of great toe of her left foot with involvement of first webspace from last three months. Plain X ray showed disrupted and necrotic proximal phalanx suggestive of diabetic foot ulcer with osteomyelitis. Despite using antibiotics and antidiabetic drugs for past three months she didn't get significant response and was suggested for toe amputaion. Hence, she approached our hospital for further treatment. We successfully treated the patient with the holistic approach of surgical debridement, medicinal leech therapy (MLT), irrigation of the wound with triphala decoction, jatyadi tail dressings, oral ayurvedic antidiabetic drugs to control blood sugar levels and a mixture of herbo mineral drug which is having antimicrobial property. DiscussionDFU may lead to infection, gangrene, amputation, death of the patient. Hence it is the need of the hour to look for limb salvage treatment modalities. ConclusionThe holistic approach of these ayurvedic treatment modalities are effective and safe in treating DFUs with osteomyelitis and in preventing amputation.

Fascial Disorders: Implications for Treatment