Control of Cavity-Induced Drag Using Steady Jets

Separated shear layer oscillations in open cavities can induce drag, noise and vibration. This issue has many aerospace applications such as Landing gears and control surfaces [1]. Recently, phase-cancellation [1] and offinstability frequency excitation [2] & [3] approaches have been incorporated in different open-loop and feedback control systems. Despite the high control performance of these systems, further enhancement is still possible. In this study, steady jets, as shown in fig. 1, are forced through 2mm, two-dimensional slots at the leading and trailing edges of the cavity. In order to study the performance of this novel approach, different cases will be examined, including: jet combination (blowing from cavity leading edge, suction from cavity leading edge and blowing-suction), jet angle (parallel or deflected jet) and jet-to-free stream velocity factor /.

Compressible flow structures interaction with a two-dimensional ejector: a cold-flow study

An experimental study has been conducted to examine the interaction of compressible flow structures such as shocks and vortices with a two-dimensional ejector geometry using a shock-tube facility. Three diaphragm pressure ratios ofP4 =P1 = 4, 8, and 12 have been employed, whereP4 is the driver gas pressure andP1 is the pressure within the driven compartment of the shock tube. These lead to incident shock Mach numbers of Ms = 1:34, 1.54, and 1.66, respectively. The length of the driver section of the shock tube was 700 mm. Air was used for both the driver and driven gases. High-speed shadowgraphy was employed to visualize the induced flowfield. Pressure measurements were taken at different locations along the test section to study theflow quantitatively. The induced flow is unsteady and dependent on the degree of compressibility of the initial shock wave generated by the rupture of the diaphragm

Suspended liquid particle disturbance on laser-induced blast wave and low density distribution

The impurity effect of suspended liquid particles on the laser-induced gas breakdown was experimentally investigated in quiescent gas. The focus of this study is the investigation of the influence of the impurities on the shock wave structure as well as the low density distribution. A 532 nm Nd:YAG laser beam with an 188 mJ/pulse was focused on the chamber filled with suspended liquid particles 0.9 ± 0.63 μm in diameter. Several shock waves are generated by multiple gas breakdowns along the beam path in the breakdown with particles. Four types of shock wave structures can be observed: (1) the dual blast waves with a similar shock radius, (2) the dual blast waves with a large shock radius at the lower breakdown, (3) the dual blast waves with a large shock radius at the upper breakdown, and (4) the triple blast waves. The independent blast waves interact with each other and enhance the shock strength behind the shock front in the lateral direction. The triple blast waves lead to the strongest shock wave in all cases. The shock wave front that propagates toward the opposite laser focal spot impinges on one another, and thereafter a transmitted shock wave (TSW) appears. The TSW interacts with the low density core called a kernel; the kernel then longitudinally expands quickly due to a Richtmyer-Meshkov-like instability. The laser-particle interaction causes an increase in the kernel volume which is approximately five times as large as that in the gas breakdown without particles. In addition, the laser-particle interaction can improve the laser energy efficiency

Quantum Hall Effect on the Grassmannians Gr2(CN)\mathbf{Gr}_2(\mathbb{C}^N)

Quantum Hall Effects (QHEs) on the complex Grassmann manifolds $\mathbf{Gr}_2(\mathbb{C}^N)$ are formulated. We set up the Landau problem in $\mathbf{Gr}_2(\mathbb{C}^N)$ and solve it using group theoretical techniques and provide the energy spectrum and the eigenstates in terms of the $SU(N)$ Wigner ${\cal D}$-functions for charged particles on $\mathbf{Gr}_2(\mathbb{C}^N)$ under the influence of abelian and non-abelian background magnetic monopoles or a combination of these thereof. In particular, for the simplest case of $\mathbf{Gr}_2(\mathbb{C}^4)$ we explicitly write down the $U(1)$ background gauge field as well as the single and many-particle eigenstates by introducing the Pl\"{u}cker coordinates and show by calculating the two-point correlation function that the Lowest Landau Level (LLL) at filling factor $\nu =1$ forms an incompressible fluid. Our results are in agreement with the previous results in the literature for QHE on ${\mathbb C}P^N$ and generalize them to all $\mathbf{Gr}_2(\mathbb{C}^N)$ in a suitable manner. Finally, we heuristically identify a relation between the $U(1)$ Hall effect on $\mathbf{Gr}_2(\mathbb{C}^4)$ and the Hall effect on the odd sphere $S^5$, which is yet to be investigated in detail, by appealing to the already known analogous relations between the Hall effects on ${\mathbb C}P^3$ and ${\mathbb C}P^7$ and those on the spheres $S^4$ and $S^8$, respectively.Comment: 34 pages, revtex 4-1, Minor Correction

Uterine sarcoma diagnose and treatment: Review article

Uterine sarcomas comprise a group of rare tumors with different tumor biology, natural history and response to treatment, contain just 3-7 of total uterine malignancies and about 1 of all gynecologic cancers. Although they cause important part of women death due gynecologic cancers. These tumors have aggressive behavior and high recurrence rate, even when confined to the uterine corpus at the time of diagnosis. The most common of uterine sarcomas is leiomyosarcoma. The incidence of leiomyosarcoma is increased after age 50. Traditionally, carcinosarcomas were named as Malignant Mixed Mullerian tumor (MMMT), but in recent classification according to their pathologic structure and its behavior, these tumors are classified as carcinomas. The rare group of sarcomas is endometrial stromal sarcoma (ESS), which occurres in younger women. In a medical studies search from 2000 to 2017, all kinds of uterine sarcomas, pathologic diagnostic methods, primary treatment and supportive treatment have been analyzed. Last histological classification is based on FIGO 2009 and WHO. According to such classification, sarcomas divided into three subtypes: leiomyosarcoma, endometrial stromal sarcoma and carcinosarcomas. Diagnosis of sarcoma before treatment and discrimination from benign myoma by current diagnostic methods is difficult. Preoperative endometrial sampling identifies only 25 of sarcomas. It may be the myometrial origin of tumor. Currently, MRI, ultrasound and PET scan may be used for the diagnosis of tumor. The gold standard of treatment is complete and intact resection of tumor considereing free margins. In advanced or recurrence disease, cytoreductive surgery followed by chemotherapy is the choice of treatment. If technically it is not possible or there are extra abdominal metastases, palliative chemotherapy should be considered. Combination of gemcitabine and docetaxel is an acceptable choice. Recent studies are going to approve the effective role for targeted agents with or without cytotoxic chemotherapy in these group of aggressive tumors. The only drug in this group has approval is pazopanib. However, it did not achieved acceptable responses in phase I, II studies. As regards of tumor biology and inappropriate response to chemotherapy and radiotherapy, sarcoma have poor prognosis in all stages. © 2018, Tehran University of Medical Sciences. All rights reserved

Control of Cavity-Induced Drag Using Steady Jets

Separated shear layer oscillations in open cavities can induce drag, noise and vibration. This issue has many aerospace applications such as Landing gears and control surfaces [1]. Recently, phase-cancellation [1] and offinstability frequency excitation [2] & [3] approaches have been incorporated in different open-loop and feedback control systems. Despite the high control performance of these systems, further enhancement is still possible. In this study, steady jets, as shown in fig. 1, are forced through 2mm, two-dimensional slots at the leading and trailing edges of the cavity. In order to study the performance of this novel approach, different cases will be examined, including: jet combination (blowing from cavity leading edge, suction from cavity leading edge and blowing-suction), jet angle (parallel or deflected jet) and jet-to-free stream velocity factor /.

Neural network control of a rehabilitation robot by state and output feedback

In this paper, neural network control is presented for a rehabilitation robot with unknown system dynamics. To deal with the system uncertainties and improve the system robustness, adaptive neural networks are used to approximate the unknown model of the robot and adapt interactions between the robot and the patient. Both full state feedback control and output feedback control are considered in this paper. With the proposed control, uniform ultimate boundedness of the closed loop system is achieved in the context of Lyapunov’s stability theory and its associated techniques. The state of the system is proven to converge to a small neighborhood of zero by appropriately choosing design parameters. Extensive simulations for a rehabilitation robot with constraints are carried out to illustrate the effectiveness of the proposed control

Sparsity enables estimation of both subcortical and cortical activity from MEG and EEG

Subcortical structures play a critical role in brain function. However, options for assessing electrophysiological activity in these structures are limited. Electromagnetic fields generated by neuronal activity in subcortical structures can be recorded noninvasively, using magnetoencephalography (MEG) and electroencephalography (EEG). However, these subcortical signals are much weaker than those generated by cortical activity. In addition, we show here that it is difficult to resolve subcortical sources because distributed cortical activity can explain the MEG and EEG patterns generated by deep sources. We then demonstrate that if the cortical activity is spatially sparse, both cortical and subcortical sources can be resolved with M/EEG. Building on this insight, we develop a hierarchical sparse inverse solution for M/EEG. We assess the performance of this algorithm on realistic simulations and auditory evoked response data, and show that thalamic and brainstem sources can be correctly estimated in the presence of cortical activity. Our work provides alternative perspectives and tools for characterizing electrophysiological activity in subcortical structures in the human brain

Dysgerminoma in three patients with Swyer syndrome

<p>Abstract</p> <p>Background</p> <p>Dysgerminoma is the most common malignant germ cell tumor of the ovary. This malignancy can be associated with pure gonadal dysgenesis or Swyer syndrome, mixed gonadal dysgenesis and partial gonadal dysgenesis.</p> <p>Case presentation</p> <p>Dysgerminoma developed in 3 phenotypic female patients with 46 XY pure gonadal dysgenesis. All patients presented first with abdominopelvic mass. Laparatomy was done. 46 XY karyotype was made by lymphocyte culture. Then these patients underwent gonadectomy that histopathology results were streak ovaries without evidence for malignancy. Two patients received postoperative adjuvant therapy.</p> <p>Conclusion</p> <p>In Patients with Swyer syndrome the risk of dysgerminoma is high and gonadectomy is recommended. Also 5% of dysgerminomas are discovered in phenotypic female and 46 XY karyotype, thus in adolescent with dysgerminoimas and amenorrhea, karyotype should be done.</p

The power of perturbation theory

We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the PicardLefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented