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Askeri Havacılık Sistemleri İçin Yüksek Güç Yoğunluklu Dönüştürücü Tasarımı
No full textAskeri havacılık sistemlerinde enerji dönüşümü; sistemlerin güvenli, kararlı ve yüksek verimli çalışabilmesi için kritik bir öneme sahiptir. Bu çalışmada, askeri havacılık platformlarına yönelik ve MIL-STD-704 standardına uygun bir DC-DC (doğru akım) dönüştürücünün tasarlanması hedeflenmiştir. Öncelikli tasarım hedefleri; anahtarlama elemanlarının üzerindeki gerilim stresinin düşürülerek daha düşük gerilim sınıfında anahtar kullanılabilmesi, akım zorlanmasının azaltılarak termal performansın iyileştirilmesi ve bu düzenlemeler sonucunda dönüştürücünün verimi ile güç yoğunluğunun artırılmasıdır. Tasarım hedefleri doğrultusunda, aynı çalışma koşullarında tek anahtarlı ileri yönlü (TAİY) ve iki anahtarlı ileri yönlü (İAİY) dönüştürücü topolojileri karşılaştırılmıştır. İAİY dönüştürücüde anahtarların maruz kaldığı maksimum gerilim stresi yaklaşık giriş gerilimi (ş) seviyesinde sınırlanırken, TAİY dönüştürücüde maksimum gerilim stresi yaklaşık 2.6ş mertebesine kadar yükselir. İAİY dönüştürücüde, iki kenetleyici diyot sayesinde transformatörün mıknatıslama endüktansında biriken enerji sıfırlandığı için ek bir resetleme sargısına ya da bastırma devresine ihtiyaç duyulmaz. İAİY dönüştürücüde, transformatörün kaçak endüktansına bağlı olarak oluşan ani gerilim yükselmeleri kenetleyici diyotlar üzerinden sönümlenir. Ayrıca, kaçak endüktanstan kaynaklanan salınımlar neredeyse tamamen ortadan kalktığı için devredeki gürültü azalır ve böylece kayıplar düşer, verim artar. İAİY dönüştürücü; yüksek giriş gerilimleri ve yüksek çıkış güçleri için daha uygun bir çalışma aralığı sunarken, devre yapısının sadeliği uygulamayı kolaylaştırır. Karşılaştırma sonucunda, İAİY topolojinin avantajları belirgin şekilde ortaya çıkmıştır ve askeri havacılık uygulamaları için İAİY topolojinin, TAİY topolojiye göre daha uygun bir seçenek olduğu gözlemlenmiştir. 270 V DC giriş gerilimi, 28 V DC çıkış gerilimi ve 560 W çıkış gücü için tasarlanan TAİY ve İAİY dönüştürücüler, tasarımın hedeflenen çıkış koşullarını sağladığının doğrulanması ve performanslarının değerlendirilmesi amacıyla MATLAB/Simulink ortamında modellenmiş ve analiz edilmiştir. Elde edilen sonuçlar, tasarlanan dönüştürücülerin standartta belirtilen 270 V DC giriş hattında çalıştırıldığında, 28 V DC çıkış gerilimini tasarım hedeflerine uygun biçimde ürettiğini göstermiştir.Energy conversion in military aviation systems is critical for ensuring safe, stable and highly efficient operation. In this study, a DC-DC (direct current) converter that suitable for military aviation platforms and compliant with the MIL-STD-704 standard is designed. The primary objectives in the design process include achieving high power density, high efficiency, low voltage stress on switches, balanced thermal distribution, low output voltage ripples, simple circuit structure, ease of control and low cost. In line with these objectives, single-switch forward (SSF) and two-switch forward (TSF) converter topologies are compared under identical operating conditions. In the TSF converter, the maximum voltage stress on the switches is limited to approximately the input voltage (Vinput) whereas in the SSF converter, the maximum voltage stress can reach approximately 2.6xVinput. In the TSF converter, the energy stored in the transformer magnetizing inductance is reset through two clamping diodes so the requirement of additional reset winding or snubber network is eliminated. Voltage spikes caused by transformer leakage inductance are also clamped through these diodes. In addition, noises reduce, losses reduce and efficiency improve because of oscillations arising from leakage inductance are almost completely suppressed. The TSF converter provides a more suitable operating range for high input voltages and high output power levels while its structural simplicity facilitates implementation. Based on the comparison, the advantages of the TSF topology become clearly evident and it is observed that the TSF topology is a more suitable option than the SSF topology for military aviation applications. SSF and TSF converter structures with a 270 V DC input, 28 V DC output and 560 W output power were designed and simulated in MATLAB/Simulink. The results show that the designed converters provide the nominal output voltage defined in the MIL-STD-704 standard at the nominal input voltage specified in standard.</p
Search for a heavy pseudoscalar Higgs boson decaying to a 125 GeV Higgs boson and a Z boson in final states with two tau and two light leptons in proton-proton collisions at TeV
No full textA search for a heavy pseudoscalar Higgs boson, A, decaying to a 125 GeV Higgs boson h and a Z boson is presented. The h boson is identified via its decay to a pair of tau leptons, while the Z boson is identified via its decay to a pair of electrons or muons. The search targets the production of the A boson via the gluon-gluon fusion process, gg → A, and in association with bottom quarks,. The analysis uses a data sample corresponding to an integrated luminosity of 138 fb−1 collected with the CMS detector at the CERN LHC in proton-proton collisions at a centre-of-mass energy of TeV. Constraints are set on the product of the cross sections of the A production mechanisms and the A → Zh decay branching fraction. The observed (expected) upper limit at 95% confidence level ranges from 0.049 (0.060) pb to 1.02 (0.79) pb for the gg → A process and from 0.053 (0.059) pb to 0.79 (0.61) pb for the process in the probed range of the A boson mass, mA, from 225 GeV to 1 TeV. The results of the search are used to constrain parameters within the benchmark scenario of the minimal supersymmetric extension of the standard model. Values of tan β below 2.2 are excluded in this scenario at 95% confidence level for all mA values in the range from 225 to 350 GeV
Politika-Dışı Q-Öğrenme ile Veri Tabanlı LQR Aktif Süspansiyon Kontrolü ve Potansiyel Enerji Kazanımı Analizi
No full textAdaptive Communication Through Exploiting RIS, SSK, and CIM for Improved Reliability and Efficiency
No full textPlant-Derived Exosomes for Enzyme Delivery in Prostate Cancer: A Narrative Perspective and Conceptual Roadmap
No full textBackground: Plant-derived extracellular vesicles (P-EVs; hereafter “exosomes”) are biocompatible, low-immunogenic, and scalable nanocarriers with inherent organotropism. Distinct lipid/protein composition and biogenesis may provide technical advantages over mammalian exosomes for loading and delivering therapeutic cargo. However, while persuasive in vitro/in vivo data support P-EV delivery of chemotherapeutics and nucleic acids, enzyme-loaded P-EVs for targeted cancer therapy—particularly in prostate cancer—remain an underexplored niche. Objective: This narrative perspective review synthesizes the technical basis, loading strategies, and translational prospects of using P-EVs specifically as enzyme-delivery platforms in prostate cancer. We highlight L-asparaginase (to exploit asparagine dependence associated with TP53 alterations) and protease-axis inhibitor proteins/peptides (e.g., targeting MMPs, cathepsins, serine proteases) as rational cargos for repeat, targeted dosing. Methods: We narratively compare P-EVs versus mammalian exosomes with respect to biocompatibility, manufacturability, and suitability for enzyme cargo; appraise passive (incubation) and active (sonication, electroporation, extrusion, chemical poration) loading with emphasis on preserving activity of labile enzymes; and propose a conceptual experimental roadmap, rather than a fixed laboratory protocol, comprising: (i) nanoparticle tracking analysis/dynamic light scattering and cryo-TEM for vesicle integrity; (ii) Western blotting for EV markers with appropriate negative-marker controls plus cargo detection; (iii) cargo-specific catalytic assays; and (iv) biodistribution and efficacy analyses within the tumor microarchitecture. Results: Existing evidence supports efficient P-EV–mediated delivery of small molecules and nucleic acids; targeted enzyme therapy is nascent but conceptually strong. Within this framework, L-asparaginase and protease-axis inhibitors emerge as rational cargos for prostate cancer, with potential for intratumoral enrichment and repeat dosing while minimizing systemic toxicity. Loading choice and rigorous QC are critical to maintain vesicle integrity, enzyme activity, and favorable distribution. Conclusion: P-EV–based enzyme delivery may enhance efficacy and reduce off-target toxicity in prostate cancer. We outline a bench-to-bedside roadmap that prioritizes GMP-compliant isolation, optimization of loading efficiency and cargo integrity, and robust in vivo biodistribution, efficacy, and safety under repeat dosing. By explicitly focusing on enzyme delivery for prostate cancer—rather than broader P-EV applications—this review delineates a specific, underexplored translational pathway for future experimental studies
KÜRESEL DÖNÜŞÜM ÇAĞINDA SÜRDÜRÜLEBİLİR EKONOMİ VE FİNANS: Yönetişim, Politikalar ve Teknolojiler
No full textChronotype and Depression: Serial Mediation of Perceived Stress and Insomnia in a Two-Wave Three-Month Longitudinal Study
No full textChronotype, a biological trait that determines an individual’s sleep-wake preferences, influences depression risk. However, the psychological and behavioral mechanisms underlying this relationship have only been examined to a limited extent in longitudinal studies. Thus, this study aims to test the impact of chronotype on depression via perceived stress and insomnia, both separately and through serial mediation. The study uses data collected at three-month intervals via a two-wave longitudinal design to explain this relationship. The study included 234 participants (51 men and 183 women) with a mean age of 22.02 (range 18–49). Perceived stress, insomnia, and depression were measured at T2 for chronotype at T1. Path analysis results showed that chronotype negatively affected perceived stress and insomnia, which indirectly predicted depression levels. Perceived stress and insomnia play a role, both separately and serially, in the longitudinal relationship between chronotype and depression. The findings show that as morningness increases, perceived stress and insomnia decrease; consequently, the risk of depression decreases as well. It should be noted that the sample predominantly consisted of young adult female university students, which may limit generalizability. These results suggest that interventions targeting stress management and sleep quality, particularly for evening-type individuals, could effectively reduce the risk of depression
Search for vector-like leptons with long-lived particle decays in the CMS muon system in proton-proton collisions at = 13 TeV
No full textA first search is presented for vector-like leptons (VLLs) exclusively decaying into a light long-lived pseudoscalar boson and a standard model τ lepton. The pseudoscalar boson is assumed to have a mass below the τ+τ− threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016–2018, corresponding to an integrated luminosity of 138 fb−1. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying τ lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime