Pitch-Based Activated Carbon Fibers: The Effect of Precursor Composition on Pore Structure

Although researchers have previously investigated the effect of precursor differences on the final properties of activated carbon fibers (ACFs), those precursors were not well-characterized. In particular, detailed information about their molecular composition and anisotropy was not available. In this study, seven oligomeric fractions, each of well-defined composition and molecular weight (mol wt) distribution, were isolated from a commercially produced isotropic petroleum pitch (i.e., Marathon M–50) and used for the production of ACFs. Four of these precursors of varying oligomeric composition were fully isotropic and three contained different levels of mesophase, so that the effects of molecular composition and molecular order were successfully isolated from each other. After the precursors were melt–spun into fibers and stabilized, they were processed by so–called “direct activation”, whereby carbonization and activation occurred simultaneously. Separate carbonization tests were also carried out in order to separate out the effects of carbonization vs. activation. Carbonization weight loss was found to be higher for fibers prepared from lower average mol wt (480–550 Da) precursors. The presence of mesophase per se did not affect weight loss during carbonization. On the other hand, activation weight loss (∼28 percent) was found to be essentially independent of precursor mol wt for all isotropic fibers. (Activation weight loss for mesophase–containing fibers was much lower.) The micropore volume of the ACFs was found to increase with decreasing precursor mol wt. However, the ratio of pores smaller than 7 Å (i.e., the desired pore size for hydrogen storage) to the total pore volume (3.9–30 Å) was found to be essentially constant for all isotropic precursors, suggesting that a similar activation mechanism occurred for all of these materials, with both new pore formation and pore widening proceeding at similar rates. For mesophase–containing precursors, on the other hand, this pore volume ratio significantly decreased with increasing mesophase content, indicating that pore widening dominates over new pore formation for this morphology. In conclusion, this study showed that the lowest mol wt precursor (i.e., a 99 percent dimer cut with a mol wt of 480 Da) attained the highest narrow micropore (≤7 Å) volume required for hydrogen storage

Tpe, Tpe Dispersion and Tpe/QT Ratio as Risk Indicators of Malign Ventricular Arrhythmia In Acute Cerebrovascular Event

INTRODUCTION: Although there are limited data on the change of Tpeak-tend (Tpe), Tpe dispersion (Tpe-d) and Tpe/QT rate, which are new predictors of ventricular arrhythmias in acute ischemic stroke (AIS) and acute hemorrhagic stroke (AHS), these parameters have not been evaluated in the transient ischemic attack (TIA). The aim of this study is to evaluate the variation of these parameters by including the TIA and performing a more detailed electrocardiographic (ECG) analysis. METHODS: In this prospective study, patients were put into three groups as 30 with AIS (mean age, 61.17+-14.14 years; 15 women/15 men), 20 with AHS (mean age, 65.05+-9.50 years; 10 women/10 men), and 30 with TIA (mean age 58.10+-13.32 years; 15 women/15 men). Thirty sex- and age-matched healthy controls were recruited. Tp-e, Tpe-d and Tp-e/QT rate were calculated from 12-lead ECG. RESULTS: In AIS and AHS both previous and new arrhythmia parameters were significantly more prolonged, compared to controls and patients with TIA. The prolonged parameter was specific to the derivations of V5 and V6. A positive correlation was present between the age, and Tpe, QTcmax and QTd (r= 0.21, p= 0.028; r= 0.19, p= 0.032; and, r= 0.22, p= 0.013, respectively) DISCUSSION AND CONCLUSION: Our study revealed that ventricular repolarization parameters such as Tpe, Tpe-d and Tpe/QT do not change in TIA, however, both AIS and AHS increase these indexes. This may explain the increased risk of ventricular arrhythmias in acute stroke patients. Moreover, in acute stroke patients, leads V5 and V6 on the ECG appear to be suitable for assessing ventricular repolarization

Nonlinear control for high-angle-of-attack aircraft flight using the state-dependent Riccati equation

В цій статті презентовано застосування методу state-dependent Riccati equation (SDRE) для проектування системи керування польотом літака, що працює в нелінійному режимі польоту. SDRE це метод нелінійного керування, який вимагає параметризації нелінійної динаміки в формі залежній від коефіцієнтів вектору стану. В регуляторі стеження реалізується подвійний контур. Невідповідності у зв'язку з факторизацією у внутрішньому контурі виправляються за допомогою нелінійного компенсатора. Для дослідження роботи SDRE регулятора використовується нелінійна модель літака.This paper presents application of the state-dependent Riccati equation (SDRE) technique for design of flight control system for a fixed-wing aircraft that operates in a nonlinear flight regime. SDRE is a nonlinear control technique that requires parameterization of the nonlinear dynamics into a state-dependent coefficient form. A dual-loop tracking controller is implemented. The mismatch due to the factorization of the inner loop is handled with a nonlinear compensator derived from the tracking control formulation. A nonlinear simulation model of the UAV is used to examine the performance of the SDRE controller.В этой статье представлено применения метода state - dependent Riccati equation (SDRE) для проектирования системы управления полетом самолета, работающего в нелинейном режиме полета. SDRE это метод нелинейного управления, требует параметризации нелинейной динамики в форме зависимой от коэффициентов вектора состояния. В регуляторе слежения реализуется двойной контур. Несоответствия в связи с факторизации во внутреннем контуре исправляются с помощью нелинейного компенсатора. Для исследования работы SDRE регулятора используется нелинейная модель самолета

3D plume modeling of SPT-100

Hall thrusters are a spacecraft propulsion device for orbit maintenance and north-south station keeping. One of the concerns about Hall thrusters is the sputtering of high energy ions which could result in the erosion of sensitive surface coatings used for solar cell elements and thermal control. In this thesis, a 3D DSMC-PIC hybrid kinetic simulation of a well known, stationary plasma thruster SPT-100 plume modeling was performed using a hybrid MPI-GPU AMR code CHAOS. Xe atoms, Xe+, and Xe+2 ions are modeled using a kinetic approach. Modeling electrons using a kinetic approach is not feasible in today's computational power for a Hall thruster plume. Thus three different models are used to compute the plasma potential. First, Boltzmann and polytropic models are used for electric potential calculations. Current density values obtained from both electron models are compared with previous experimental measurements and simulations in the literature. It was seen that the polytropic model shows better agreement with the experimental measurements than the Boltzmann model and previous studies. In order to implement more detailed models, an electron fluid model is implemented and is solved on an AMR octree grid using the preconditioned conjugate gradient method. Current density comparisons of the electron fluid model with the experimental measurements showed a worse comparison than the polytropic model for the selected parameters. The implemented electron fluid model is then compared with ion energy distributions from flight measurements and previous simulations and showed good agreement for the chosen parameters. In order to investigate the influence of solar panel voltage on a spacecraft plume, simulations using the electron fluid and the polytropic models were compared. It was seen that the spatial distribution of ions in the core plume and in the backflow region are similar for both electron models. Finally, sputtering calculations were performed and it was seen that the energies of ions that hit the solar panel are smaller than the threshold energy of aluminum, and so that there would be insignificant sputtering. This is because neutralized particles in the vicinity of the solar panel create a shield that protects the solar panel from the high energy CEX ions

Refugee Students in Public Schools: Guidelines for Developing Inclusive School Counseling Programs

This paper identifies key experiences of refugee students and reviews how these children integrate into the formal schooling system in America. Refugee children face specific challenges, and counseling services are critical for the students’ success. Guidelines on counseling refugee students are limited. The purpose of this article is to provide guiding suggestions for school counselors to effectively help refugee students by identifying roles, responsibilities, and functions of school counselors using the ASCA National Model

Birlikte Sarkan Yük Taşıyan Kol Uçuşundaki Quadrotorların Modellemesi ve Kontrolü

TÜBİTAK EEEAG01.09.2016Insansız hava araçlarının (IHA) kol uçusu bazı avantajları nedeniyle gittikçe daha çok önemkazanmaktadır. Örnegin afetlerde arama sırasında kol uçusu yapan insansız hava araçları iledaha genis bir alanın daha kısa sürede aranması mümkün olabilir. Yine göçmen kuslar gibibirbirini takip ederek öndeki aracın dümen suyunda (wake) uçan insansız hava araçlarındayakıt tüketiminin daha az olacagı da bilinmektedir. Diger yandan kol uçusu ile tek basınayapılamayacak görevlerin yerine getirilebilmesi mümkündür. Bunlar arasında çok fazla dikkatçekmemis bir konu, iki veya daha fazla quadrotorun (dört-pervanelinin) bir yükü birliktetasımasıdır. Birlikte sarkan yük tasıma geçmiste insanlı helikopterler için düsünülmüs vearastırılmıstır. Quadrotorlar da helikopterler gibi dikine inis kalkıs yapmaktadır. Buna karsılıkbasit yapıları nedeniyle özellikle küçük insansız hava aracı görevleri açısından tercihedilmektedirler. Bu projede, 2 ve 3 quadrotorun bunlara baglanmıs sarkan bir yükü birliktetasıması modellenecek kol uçusu yaparak birlikte yük tasıyan bu quadrotorlar için gerekli uçuskontrol algoritmalarının gelistirilmistir.Unmanned air vehicles (UAVs) in a formation may carry out various missionsthat are not possible through a single vehicle. Such Formation flying aircraft mayspeed up search and rescue operations by covering a wider area more rapidly.Aircraft, just like migrating birds, flying at each other’s wake result in less fuelconsumption. There are many missions that may be impossible for a single UAVbut possible when they are flying in formation. Among others on such missionsthat has not been addressed in depth in literature is the slung load carryingquadrotor formations. Carrying a slung load has been considered and addressedfor manned helicopters in the past. Quadrotors, just like helicopters can take offand land vertically. However, due to their simpler construction, they are preferredover helicopters in small unmanned missions. In this project, quadrotors carryinga single slung load is modelled and neccessary flight control algorithms aredeveloped.Keywords: Quadrotor, Unmanned air vehicle, formation flight, formation control,slung load carrying, automatic flight control, collaborative contro

Terapötik Bir Araç Olarak Bağışlama: İyileştirici Etken OlarakBağışlama Olgusunun Psikolojik Danışma Sürecinde Kullanımı

Interpersonal conflicts and misunderstandings are unavoidable in relationships. Sincehumans are social, relational beings, it is very natural that the problems about which clients seekhelp in counseling are rather interpersonal problems. In order for counselors to be effectivelyhelpful in the counseling process, it is important that therapists are knowledgeable in the conceptof forgiveness, processes of forgiveness and the use of forgiveness as a theraputic tool. This paperpresents the use of forgiveness as a therapeutic tool to help the clients to deal with a brokenheart, being hurt in interpersonal relationships and even dealing with traumatic experiences.The information provided are the concept and process of forgiveness, forgivingness as apersonality trait, and forgiveness and mental health. In addition, forgiveness is discussed in thecounseling process as a therapeutic tool to help clients deal with transgressions in interpersonalrelationships. Kişilerarası ilişkilerde çatışmalar ve anlaşmazlıklar kaçınılmazdır. İnsanlar ilişki odaklıtoplumsal varlıklar oldukları için danışanların psikolojik danışma sürecinde yardım aradıklarıproblemlerinin temelinde kişilerarası ilişkilerin yatması çok doğaldır. Danışanlara psikolojikdanışma sürecinde etkili bir şekilde yardımcı olabilmek için psikolojik danışmanların bağışlamakavramı ve süreci ve bağışlamanın iyileştirici bir etken olarak kullanılmasını bilmeleri önemlidir.Bu çalışmada danışanların kişilerarası ilişkilerde yaşadıkları kalp kırıklıkları, incinmeler ve hattatravmatik deneyimler ile baş etmelerine yardımcı olmak için bağışlama olgusunun iyileşmeyikolaylaştırıcı terapötik bir araç olarak kullanılması üzerinde durulmuştur. Buna bağlı olaraköncelikle bağışlama kavramı ve bağışlama süreci, bir kişilik özelliği olarak bağışlayıcılık vebağışlamanın ruh sağlığı ile ilişkisi hakkında bilgi verilmiş, daha sonra ikili ilişkilerde yaşananolumsuz duygularla baş etme araçlarından biri olarak bağışlamanın psikolojik danışmasürecindeki yeri tartışılmıştır

Young Leaders of Character Program: A Model of Character Education Program for Improving Life Effectiveness Skills and Civic Responsibility of Adolescents

Studies that examine character development programs are scarce. This study examines the effect of a week-long character education program in a range of life skills and civic efficacy. Thirty adolescents participated in the training. A no-control, quasi-experimental design incorporated baseline measures and a six-month follow-up. A Life Effectiveness Questionnaire and Civic Efficacy Survey were administered and open-ended questions further explored how participants incorporated program outcomes into their daily lives. The t-test comparison of baseline and pretest measures yielded no significant differences, but t-test comparison of pre-post- test analysis elicited statistically significant positive results. Findings indicate the program can provide a model for character education that fosters adolescents’ sense of agency as leaders and citizens

Young Leaders of Character Program: A Model of Character Education Program for Improving Life Effectiveness Skills and Civic Responsibility of Adolescents

Studies that examine character development programs are scarce. This study examines the effect of a week-long character education program in a range of life skills and civic efficacy. Thirty adolescents participated in the training. A no-control, quasi-experimental design incorporated baseline measures and a six-month follow-up. A Life Effectiveness Questionnaire and Civic Efficacy Survey were administered and open-ended questions further explored how participants incorporated program outcomes into their daily lives. The t-test comparison of baseline and pretest measures yielded no significant differences, but t-test comparison of pre-post- test analysis elicited statistically significant positive results. Findings indicate the program can provide a model for character education that fosters adolescents’ sense of agency as leaders and citizens

Controlling a CyberOctopus Soft Arm with Muscle-like Actuation

This paper presents an application of the energy shaping methodology to control a flexible, elastic Cosserat rod model of a single octopus arm. The novel contributions of this work are two-fold: (i) a control-oriented modeling of the anatomically realistic internal muscular architecture of an octopus arm; and (ii) the integration of these muscle models into the energy shaping control methodology. The control-oriented modeling takes inspiration in equal parts from theories of nonlinear elasticity and energy shaping control. By introducing a stored energy function for muscles, the difficulties associated with explicitly solving the matching conditions of the energy shaping methodology are avoided. The overall control design problem is posed as a bilevel optimization problem. Its solution is obtained through iterative algorithms. The methodology is numerically implemented and demonstrated in a full-scale dynamic simulation environment Elastica. Two bio-inspired numerical experiments involving the control of octopus arms are reported