Voice quality after radiation therapy of early glottic cancer

Radiation therapy is generally accepted as a successful treatment modality forearly glottic cancer offering an acceptable voice quality after the treatment. In order to evaluate objectively the voice quality in irradiated patients and to eliminate the influence of decreasing voice quality as a result of normal aging, the results of the acoustic analysis of voice in 20 patients with early glottic cancer treated with radiation therapy were compared to the results of 20 age-matched volunteers. The results established worse voice quality in the irradiated group but the difference was not significant except in amplitude perturbation quotient which expresses the instability of loudness. In order to identity the factors which could influence the quality of voice after irradiation of the laryngeal carcinoma, the results of laryngoscopy and the biopsy extension, were correlated with theresults of the perceptive voice evaluation and the results of acoustic voice analysis. No significant influence of the stated factors on the voice quality of the patients was established. Only the irregular glottic gap duringphonation indicated to be connected with very hoarse voice. In conclusion, radiation therapy of early glottic cancer results in an abnormal, but still satisfactory voice quality when compared to the voice quality of normal age-matched speakers. The hoarseness is the results of instability of pitch and specifically the instability of amplitude (loudness). The voice quality after the treatment can be influenced by the tumor extension and localization, the sequels of excisional biopsy, and the radiation therapy or functional disorder. All the stated factors are very intermingled and are probably acting together

Multiaxial Fatigue Criteria for Random Stress Response – Theoretical and Experimental Comparison

AbstractRandomly excited structures are exposed to random stress loads that can result in fatigue failure. Prediction of such failure requires good structural dynamics and fatigue models. This study researches the multiaxial criteria which reduce the multiaxial stress state to an equivalent uniaxial stress. Several frequency-domain criteria can be found in literature. However, experimental comparison studies are scarce. This research presents and then theoretically and experimentally compares selected frequency-domain multiaxial criteria, namely: maximum normal stress, maximum shear stress and the C-S criterion. Time-to-failure results are compared across multiaxial criteria and with experimental data. Results show that selected methods give reliable estimates

Priporočila za obravnavo bolnikov z malignimi limfomi

no abstractni abstrakt

Modal-interaction approach to the strong structural-acoustic coupling of an elastic Helmholtz resonator and an acoustic cavity containing a heavy fluid

This paper focuses on the development of a method for the accurate representation of the strong structural–acoustic coupling between an elastic Helmholtz resonator, a heavy fluid and an impedance tube. The Helmholtz resonator has an elastic wall and is connected to the impedance tube, yielding a system with two acoustic cavities coupled through a neck and the fluid–structure interaction between a liquid medium and a plate. The proposed analytical formulation is based on the modal superposition method in combination with a lumped parameter model of the neck. The effect of the evanescent waves is taken into account in the form of both the inertial attached length of the neck and the terms of the evanescent pressure modes in the governing equations, which are omitted in other methods. The formulation of the evanescent pressure field is redefined to include the reflected waves, thus expanding the application to the acoustic cavity of an arbitrary shape. Strong coupling between the heavy fluid and the plate is accomplished with the implementation of the non-resonant acoustic modes. Furthermore, the improved performance of the model for moderately thick plates is achieved with the combined approach of the Mindlin–Reissner theory mode shapes and the Kirchhoff–Love theory governing equations. The proposed model is validated with FEA simulations of three different resonator configurations and compared to other applicable methods. The results demonstrate substantially increased accuracy in the predicted response of the coupled structural–acoustic system

Ekvivalenca harmonskih in impulznih obremenitev v vibracijskem utrujanju

In vibration fatigue, three unique types of loads are typical: random, harmonic and impulse. In an application any of these loads are possible. A fatigue-life analysis is possible in the time and frequency domains using the frequency-response function of a structure. Recent studies demonstrated that the impulse loads influence the accuracy of a fatigue-life prediction in the frequency domain. The focus of this research is a theoretical study of an equivalent harmonic load to the impulse load on a single-degree-of-freedom system in order to investigate the feasibility of impulse loads in vibration testing. This research shows that there is a relationship between the impulse and harmonic loads that is related to the underlying dynamic properties (e.g., damping, natural frequency). Based on a theoretical analysis an experimental procedure was developed for both cases of excitation, which was able to confirm the theoretical analysis. Using the modal decomposition the single-degree-of-freedom approach can be generalized to multiple-degrees-of-freedom systems

Expansion of the dynamic strain field in 3D-printed structures using a hybrid modeling approach

The 3D printing of machine components is becoming an established technique. To ensure their robustness and longevity, it is crucial to numerically predict the dynamic response of these components in a variety of operating conditions. Dynamic properties are conventionally obtained in the form of displacement or strain-based response models. However, numerical modeling of the dynamic properties of 3D-printed structures can be a tedious task, mainly due to the complex geometry of the infill pattern and the influence of the printing parameters on the material and geometric properties. Alternatively, the dynamic properties can also be represented in the form of an experimental response model. This reflects the real dynamic properties, but is usually subject to measurement errors and has a low spatial resolution. To integrate the benefits of numerical and experimental response models, we propose a hybrid modeling approach with the System Equivalent Mixing method. The method was extended to a form that could integrate dynamic response models with different physical quantities (displacement and strain). The approach was then analyzed on a 3D-printed beam with a complex infill pattern, where an accurate expansion of the strain response to a high spatial resolution was demonstrated

LARYNGEAL PAPILLOMATOSIS

Background. Laryngeal papillomatosis is a rare disease of the upper respiratory tract, which may have a dramatic course. The results of many studies have proved a viral etiology, but the precise mode of the virus transmission remains indistinct. Surgery is the most successful mode of treatment. Adjuvant therapy is indicated only in an aggressive form of the disease.Patients. In the last 23 years, 136 patients have been treated for laryngeal papillomatosis at the Department of Otorhinolaryngology and Cervicofacial Surgery in Ljubljana. All patients were treated surgically; since 1995, CO2 laser has been used. Eighteen patients with aggressive disease received adjuvant therapy. Only in 2.2% of patients was tracheotomy necessary. In 9.6% of patients, laryngeal scarring occurred as a result of repeated surgical procedures. In 2.2%, malignant alteration of laryngeal papillomatosis developed.Conclusions. The outcome of treatment of laryngeal papillomatosis in Ljubljana is comparable to the results of other centres. As carcinoma may develop, although very rarely, more than 10 years after the onset of laryngeal papillomatosis, all patients must be followed carefully.</p

On the estimation of structural admittances from acoustic measurement using a dynamic substructuring approach

A reconstructed displacement field using near-field acoustic holography (NAH) serves as an alternative to conventional measurement methods when it comes to obtaining the high-resolution vibration response of a structure. The method is highly applicable as it enables direct, non-contact measurement of the 3D structural response based on a single acoustic measurement. Although useful, the method\u27s ill-posed nature limits its use in the field of structural dynamics. This problem can be effectively addressed by using regularization and/or field-separation techniques that can attenuate the noise and the presence of external acoustic sources. All these methods rely on the measurement of acoustic quantitiestherefore, the reconstruction of structural admittances is based solely on the evaluation of the hologram(s). This article proposes an alternative approach to improving the accuracy of NAH-based structural admittances by integrating them with a few discrete response measurement on the structure itself. The formulation relies on the mixing of the high-resolution NAH measurement with accurate discrete measurements (e.g., accelerometer or laser vibrometer) using dynamic substructuring techniques. The proposed hybrid approach is a very powerful modeling methodology that can integrate high-resolution spatial measurements using NAH with the accuracy and consistency provided by precise translation discrete measurements. In order to mix two experimental response models System Equivalent Model Mixing (SEMM) method is proposed. An experimental case study on a T-shaped structure demonstrates the robustness and improved accuracy of the estimated structural admittances compared to the plain NAH formulation

A Sequential Approach to the Biodynamic Modeling of a Human Finger

In an effort to understand the vibration-induced injuries incurred by manual workers, mechanical models are developed and used to predict the biodynamic responses of human body parts that are exposed to vibration. Researchers have traditionally focused on the arms and hands, but there has been only limited research on finger modeling. To simulate the accurate response of a single finger, a detailed mechanical model based on biodynamic finger measurements is necessary. However, the development of such models may prove difficult using the traditional one-point coupling method; therefore, this study proposes a new approach. A novel device for single-finger measurements is presented and used to expose the finger to a single-axial broadband excitation. The sequentially measured responses of the different finger parts are then used to identify the parameters of a multibody mechanical model of the index finger. Very good agreement between the measured and the simulated data was achieved, and the study also confirmed that the obtained index-finger model is acceptable for further biodynamic studies