State-of-the-Art of Thermal Control Solutions to Establish a Modular, Multi-Orbit Capable Spacecraft Thermal Management System Design Methodology

Today, the exploration and exploitation of space continues to become a more common occurrence. All types of spacecraft (S/C) utilize various types of thermal management solutions to mitigate the effects of thermal loading from the unforgiving vacuum of space. Without an appropriately designed thermal system, components on-board the S/C can experience failure or malfunction due to fluctuations in temperatures either beyond the designed operational parameters or unstable oscillating temperatures. The purpose of this study is to perform a comprehensive review of technologies available today that are being used for thermal management onboard S/C in addition to investigating the means to analyzing the environment allowing the establishment of a design methodology that would support the development of efficient and effective future spacecraft thermal control systems. A combination of thermal solutions are investigated that would best assist onboard components in maintaining operable thermal ranges. Modern day methods of analyzing and understanding these environments were looked at to provide an insight as to what may be available for both the new and experienced developer. Analytical methods varied, dependent on a reference point, but the outcomes were similar in that the primary concern of heat loading in space is radiative heating from internal and external sources. Numerically, industry has continued to find new ways of understanding environments prior to launch whether it be through analytical estimation or numerical tools. Thermal control solutions consisted of coatings, insulation, heat pipes, phase change material, conductive materials, thermal devices, actively pumped fluid loops, radiators, and combinations of these systems. With numerous technologies identified, a series of charts were created to provide comparatives among the various aspects of selection guiding the start of design. Lastly, utilizing the knowledge gained from such a wide-net review of thermal control solutions available today, both in space and terrestrially, a design methodology was established

Advances in Spacecraft Thermal Control

Spacecraft thermal management is critical for ensuring mission success, as it affects the performance and longevity of onboard systems. A comprehensive overview of the state of the art in spacecraft thermal control solutions, as well as a design methodology framework for efficient and effective thermal management, is provided. Various thermal control solutions, including coatings, insulation, heat pipes, phase-change materials, conductive materials, thermal devices, actively pumped fluid loops, and radiators, are discussed along with the primary sources of heat loading in space. The need for accurate modeling and analysis of the thermal environment to identify appropriate thermal control solutions and design pathways is highlighted. Future innovations in thermal management, such as new materials and technologies that have the potential to further improve the efficiency and effectiveness of thermal control solutions for spacecraft, are explored

A rare case of solitary fibrous tumor of the temporal region: 7-year-follow-up clinical-radiographic evaluation and literature review

Solitary fibrous tumor is a rare spindle-cell neoplasm of mesenchymal origin. In head and neck region, the tumors present slow-growing masses, often with local compressive symptoms. Although it is generally benign, malignant variants have been identified. The radiological diagnosis of solitary fibrous tumor is usually based on computer tomography and/or magnetic resonance imaging. Microscopically, a solitary fibrous tumor is characteristically a circumscribed neoplasm composed of variably cellular and patternless distributions of bland spindle and ovoid cells within variably collagenous stroma that frequently shows areas of dense hyalinisation, as well as interspersed large branching or “staghorn”- shaped thin-walled vessels. Immunohistochemical staining is very effective to distinguish solitary fibrous tumors from other fibroblastic tumors. Recently, NAB2–STAT6 gene fusion derived from inv12 (q13q13) has been reported as the genetic hallmark of solitary fibrous tumor. Complete local surgical excision appears to be the treatment of choice for solitary fibrous tumor of the head and neck region. Recurrence was reported in 5% of cases. The median recurrence-free interval was 36.5 months. We report the case of a solitary fibrous tumor of the temporal region, surgically excised and with no clinical and/or radiological signs of recurrence after 7 years of follow-up

Enucleation of a multilocular odontogenic keratocyst using sagittal osteotomy: A case report

Odontogenic keratocysts are significant cysts of the jaw that are characterized by aggressive behavior and a high tendency to recur. The treatments of choice may be radical or conservative, and in the literature a debate is still open about the gold standard in the treatment of OKCs.This report describes a wide multilocular OKC extended in the right mandibular ramus and illustrates atypical behavior of a cystic lobe after marsupialization, not found to our knowledge in the previous literature. Moreover, an orthognathic procedure, consisting of sagittal osteotomy was chosen for the excision of the cyst to preserve as much bone as possible and the integrity of the inferior alveolar nerve

Correlation between density and resorption of fresh-frozen and autogenous bone grafts

Trial Design. This analysis compared the outcome of fresh-frozen versus autologous bone block grafts for horizontal ridge augmentation in patients with Cawood and Howell class IV atrophies. Methods. Seventeen patients received autologous grafts and 21 patients received fresh-frozen bone grafts. Patients underwent CT scans 1 week and 6 months after surgery for graft volume and density analysis. Results. Two autologous and 3 fresh-frozen grafts failed. Autologous and fresh-frozen grafts lost, respectively, 28% and 46% of their initial volume (P = 0.028). It is noteworthy that less dense fresh-frozen blocks lost more volume than denser grafts (61% versus 16%). Conclusions. According to these 6-month results, only denser fresh-frozen bone graft may be an acceptable alternative to autologous bone for horizontal ridge augmentation. Further studies are needed to investigate its behaviour at longer time points

Excitation of self-localized spin-wave "bullets" by spin-polarized current in in-plane magnetized magnetic nano-contacts: a micromagnetic study

It was shown by micromagnetic simulation that a current-driven in-plane magnetized magnetic nano-contact, besides a quasi-linear propagating ("Slonczewski") spin wave mode, can also support a nonlinear self-localized spin wave "bullet" mode that exists in a much wider range of bias currents. The frequency of the "bullet" mode lies below the spectrum of linear propagating spin waves, which makes this mode evanescent and determines its spatial localization. The threshold current for the excitation of the self-localized "bullet" is substantially lower than for the linear propagating mode, but finite-amplitude initial perturbations of magnetization are necessary to generate a "bullet" in our numerical simulations, where thermal fluctuations are neglected. Consequently, in these simulations the hysteretic switching between the propagating and localized spin wave modes is found when the bias current is varied.Comment: 27 pages, 5 figures, paper submitted to Physical Review

Migraine and Cranial Autonomic Symptoms in Children and Adolescents: A Clinical Study

The frequency of cranial autonomic symptoms in children affected by primary headaches is uncertain. The aim of our study was to estimate the frequency of symptoms in pediatric headaches and correlate it with main migraine characteristics. A questionnaire investigating the presence of cranial autonomic symptoms was administered to all children with primary headache for 2 years. A total of 230 children with primary headache (105 males, 125 females) were included. Two hundred two children were affected by migraine and 28 (12.2%) by other primary headaches. Cranial autonomic symptoms were significantly complained by migraineurs (55% vs 17.8%) (P < .001) and by children with higher frequency of migraine attacks (odds ratio = 2.6, confidence interval = 1.4-4.7, P = .001). Our findings show that cranial autonomic symptoms are rather common during pediatric migraine attacks. The association between cranial autonomic symptoms and higher frequency of attacks might suggest the role of the trigeminal-autonomic reflex in migraine pathophysiolog