Defection-Proofed? Militaries and Authoritarian Regime Survival

The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especially with the resilience of many of these regimes over most of world history and over the past few decades in particular. Autocratic leaders need to secure the support of their militaries to survive in office and to minimize the risk of a coup. Among the commonly employed mechanisms in this regard is the extension of extra-budgetary financial rewards, including ‘Military-Owned Businesses (MOBs).’ Nevertheless, under the increasingly significant threat of an uprising from below, military defection remains the key for the success of the revolution. The question then becomes: under what conditions would a military defect from an autocratic ruling alliance? Although many answers have been proposed to solve this puzzle, an increasing number of cases are proving them insufficient. Alternatively, this project presents one novel answer to this question, which is: militaries are “defection-proofed” in the face of mass uprisings when they develop financial dependency on the regime. By contrast, when the management of the extra-budgetary resource for the military, i.e. MOBs, becomes the exclusive domain of the military and independent from the regime, the military is expected to defect. This proposed hypothesis represents a contribution to the democratization literature, both its installation, i.e. underlining a ‘pro-democracy’ capacity of the military in removing the dictator, as well as its consolidation, i.e. handling the legacy of the autocratic regime after the transition. This hypothesis is tested comparatively against the cases of mass protests in China (1989), Indonesia (1998), Thailand (2006), Iran (2009), and Egypt (2011). This comparative analysis represents another contribution of this study, bringing together a diverse array of cases unexpected to have much in common. Analysis draws on a mix of both primary resources collected from the field along with secondary materials. The comparisons are made considering the type of civil-military relations in each case, the size and type of financial rewards controlled by the military, and their effect, if any, on its decision to repress or defect based on the interaction between the military and the dictator

Design of Observer-Based Robust Power System Stabilizers

Power systems are subject to undesirable small oscillations that might grow to cause system shutdown and consequently great loss of national economy. The present manuscript  proposes two  designs for observer-based robust power system stabilizer (PSS) using Linear Matrix Inequality (LMI) approach to damp such oscillations. A model to describe power system dynamics for different loads is derived in the norm-bounded form. The first controller design is based on the derived model to achieve  robust stability against load variation. The design is based on a new Bilinear matrix inequality (BMI) condition. The BMI optimization  is solved interatively in terms of Linear Matrix Inequality (LMI) framework. The condition contains a symmetric positive definite full matrix to be obtained, rather than the commonly used block diagonal form. The difficulty in finding a feasible solution is thus alleviated. The resulting LMI is of small size, easy to solve. The second PSS design shifts the closed loop poles in a desired region so as to achieve a favorite  settling time and damping ratio via a non-iterative solution to a set of LMIs.  The approach provides a systematic way to design a robust output feedback PSS which  guarantees good dynamic performance for different loads. Simulation results based on single-machine and multi-machine power system models verify the ability of the proposed PSS to satisfy control objectives for a wide range of load conditions

Optimal PV Allocation & Minimal tap-Changing Transformers Achieving Best Distribution Voltage Profile & Minimum Losses in Active Distribution Networks

In distribution systems, voltage levels of the various buses should be maintained within the permissible limits for satisfactory operation of all electrical installations and equipment.  The task of voltage control is closely associated with fluctuating load conditions and corresponding requirements of reactive power compensation. The problem of load bus voltage optimization in distribution systems that have distributed generation (DG) has recently become an issue. In Oman, the distribution code limits the load bus voltage variations within ±6% of the nominal value. Several voltage control methods are employed in active distribution systems with a high share of photovoltaic systems (PV) to keep the voltage levels within the desirable limits. In addition to the constraint of targeting the best voltage profile, another constraint has to be achieved which is the minimum loss in the distribution network. An optimised solution for voltage of load busses with on-load tap-changing (OLTC) tarnsformers and PV sources is presesnted in this paper. This study addresses the problem of optimizing the injected power from PV systems associated with the facilities of tap-changing transformers, as it is an important means of controlling voltage throughout the system.  To avoid violating tap-changing constraints, a method is depicted for determining the minimal changes in transformer taps to control voltage levels with distributed PV sources.  The taps of a range + 5 to -15 %, can be achieved by tap-changing transformers. The OLTC operation was designed to keep the secondary bus within the voltage standard for MV networks

Design of Robust Digital Pole Placer for Car Active Suspension with Input Constraint

This chapter deals with the problem of state feedback control for an active quarter-car suspension system with control input constraint. The dynamics of the suspension system is first formed in terms of the control objectives: ride comfort, suspension deflection, and maximum actuator control force. The control task is formulated as robustly placing the closed poles in a desired region against different passenger load. Since digital computers are widely used in the vehicle industry, a new saturated controller design method is presented for regional pole-placement of uncertain discrete time systems. The constraint of control input saturation is considered in the design phase. The desired dynamic performance for uncertain discrete-time systems is represented by the settling time and damping ratio. A sufficient condition is derived to place the poles in a desired region. The design is formulated in terms of linear matrix inequality optimization. The effectiveness of the proposed design is illustrated by applying it to a quarter?car active suspension system. Different road tests for the proposed controller are carried out: step and bump disturbances. The proposed design achieves the desired oscillation damping due to road disturbances in addition to passenger comfort. The results are compared with the passive suspension system

Clinical Evaluation of 660 nm Diode Laser Therapy on the Pain, Size and Functional Disorders of Recurrent Aphthous Stomatitis

BACKGROUND: Minor recurrent aphthous stomatitis (MiRAS) is one of the most common, recurrent, and painful mucosal pathological condition. It is characterised by round or shallow oval ulcers, less than 10 mm in diameter, surrounded by a thin erythematous halo. It involves non-keratinized mucosa such as the labial and buccal mucosa, the ventral surface or borders of the tongue and the floor of the mouth, but it is uncommon to occur on the keratinised mucosa. It heals spontaneously within 10-14 days without scarring. There is no curative remedy to prevent its recurrence; also, available modalities only reduce the symptoms and severity of the lesion. AIM: Since these lesions may be extremely painful, we decided to estimate the pain-relieving and healing properties of low energy level laser therapy using diode laser 660 nm on MiRAS. MATERIAL AND METHODS: Twenty healthy patients suffering from minor aphthous ulcers were randomly selected from the Out-Patient Clinic of Oral Medicine Department, Faculty of Dentistry, Alexandria University. They were equally divided into two groups, study group who received 660 nm diode laser irradiation while the control group received placebo (sodium bicarbonate rinse). The visual analogue scale, size reduction, effectiveness indices and functional disorders were compared between the groups. RESULTS: Both groups presented a statistically significant difference from baseline to follow up periods. But, diode laser 660 nm treatment showed more remarkable improvements in reduction of healing time, pain and lesion size. CONCLUSION: We concluded that diode laser 660 nm should be further considered as an effective alternative therapeutic regimen to patients who suffer from recurrent aphthous stomatitis

Harmonic Distortion Reduction of Transformer-Less Grid-Connected Converters by Ellipsoidal-Based Robust Control

A photovoltaic generator connected to a large network and supplying a nonlinear load (source of harmonics) injects distorted current into the grid. This manuscript presents an invariant-ellipsoid set design of a robust controlled active power filter to inject current into the large grid with minimum total harmonic distortion (THD). The nonlinear load current is considered an external disturbance to minimize its effect on the injected grid current. Moreover, the large grid is modeled as a fixed voltage source in a series with a Thevenin impedance whose value changes within an interval. Using the invariant-ellipsoid technique, the problem is cast as a robust disturbance-rejection tracking control. The volume of the ellipsoid is minimized, which results in minimizing the effect of disturbance on system performance and keeping the trajectories as close as possible to the origin. The design is cast into a set of nonlinear matrix inequalities that are linearized by fixing a scalar. The resulting convex optimization is solved iteratively by linear matrix inequalities (LMIs). The simulation and experimental findings show that the proposed design is successful in reducing THD injected into the grid when grid impedance is uncertain and variable loads are applied (balanced and unbalanced cases)

A Study Comparing the Effectiveness of Hamstring Tendon Graft Versus Quadriceps Tendon Graft in Press Fit Anterior Cruciate Ligament Reconstruction

Background: Press fit ACL reconstruction is a surgical procedure used to repair a torn anterior cruciate ligament (ACL) in the knee. During press fit ACL reconstruction, a graft is used to replace the torn ACL. The graft can be harvested from various sources, such as the patient's own hamstring tendons or patellar tendon, or from a donor. The graft is then inserted into tunnels created in the femur and tibia bone. The term "press fit" refers to the technique used to secure the graft within these bone tunnels. Instead of using screws or other fixation devices, press fit ACL reconstruction relies on tight fitting of the graft within the tunnels. Objective: This study aimed to compare the subjective, objective, and radiological results of press fit anterior cruciate ligament (ACL) reconstruction using hamstring tendon graft versus quadriceps tendon graft. Methods: A total of 50 patients with complete ACL tears underwent press fit ACL reconstruction between March 2016 and June 2019. Among them, 25 patients received a hamstring tendon graft, and another 25 patients received a quadriceps tendon graft. Results: The study demonstrated favorable outcomes of press fit ACL reconstruction, with improvements observed in all 50 patients when comparing postoperative to preoperative parameters. The results also showed comparable outcomes between the quadriceps and hamstring groups in terms of subjective, objective, and radiological measures. Conclusion: The press fit technique for ACL reconstruction is a successful method of graft fixation that offers advantages such as fewer complications, lower cost, and easier revision compared to other commonly used techniques

Predictor factors of sustained virological response in patients with chronic hepatitis C treated with current direct-acting antiviral drugs

Purpose: To assess the efficacy and predictors of treatment response of chronic hepatitis C genotype 4 Egyptian patients with sofosbuvir and daclatasvir, with or without ribavirin.Methods: This prospective study enrolled 200 patients with chronic hepatitis C virus (HCV) genotype 4 infection who received sofosbuvir plus daclatasvir for 12 weeks, with the addition of ribavirin for treating cirrhotic patients. Immunological parameters such as natural killer (NK) cell percentage, phenotype, and serum C-X-C motif chemokine 10 (CXCL10) were evaluated prior to treatment and at the end of the treatment.Results: Overall, 92.5 % of the patients achieved sustained virological response at 12 weeks (SVR12), where the non-cirrhotic group had 96.29 % SVR12, while the cirrhotic group had 84.61 % SVR12. Nonresponders had lower pretreatment platelet count, higher CXCL10 levels, and lower baseline frequencies of NK cells and NK subgroup CD56- CD16+.Conclusion: Based on these results, the use of sofosbuvir plus daclatasvir with or without ribavirin for 12 weeks, is an effective regimen in the treatment of Egyptian patients infected with genotype 4 HCV. The predictors of non-response are advanced age, liver cirrhosis, lower pretreatment platelet count, higher level of CXCL10, lower baseline NK cells frequency and percentage of the dysfunctional subset CD56- CD16+. Keywords: Hepatitis C virus, Genotype 4, Sofosbuvir, Daclatasvir, Sustained virological respons

Roust Power System Stabilizer Design Using Kharitonov’s Theorem: A Case Study

This paper proposes a robust power system stabilizer(PSS) for a steam synchronous generator in Barka II power station. The PSS should be capable of damping small-disturbance oscillations (inherently existing in power systems due to e.g. load changes, lines switching...etc.) within a certain settling time for different load conditions. Also, the proposed PSS must have the conventional structure and its parameters must not be violated. To achieve this goal, robust control provides many advantages. The suggested controller is tuned by the  Kharitonov’s theorem and uses the standard structure employed in industry. The problem is cast into a nonlinear constrained optimization problem to achieve the desired settling time without violating the practical values of the controller parameters. Performance of the robust PSS is evaluated by several simulations in the presence of system uncertainty due to load changes