Entwicklung und Erprobung eines bordautonomen Flugführungskonzeptes für das Luftschiff ALUSTRA MOEWE

Der heutige Einsatz von UAVs findet in vielen Bereichen statt. Deren Spektrum erstreckt sich von der zivilen Nutzung wie zum Beispiel bei Such- und Rettungsmissionen, Luftbildfotografie, industriellen Überwachungsaufgaben im Bereich Sicherheitsmanagement bis hin zu militärischen Einsätzen, wie Aufklärung, Überwachung, aber ebenso Kampfeinsätze. Im Rahmen des Forschungsvorhabens ALUSTRA MOEWE wird ein funktionsfähiges autonomes mit Helium befülltes Luftschiff aufgebaut, das als Kamera-Plattform für die 3DModellierung von Gebäuden und der Erdoberfläche zum Einsatz gelangen soll. Dazu werden Flugführungs- und Regelungstheorien zu einem durchgängigen Gesamtkonzept zusammengeführt, die es erlauben, unter Berücksichtigung der entsprechenden Gebäude beziehungsweise über die Landschaften fliegen und mittels einer digitalen Kamera Aufnahmen zu erstellen. Diese Aufnahmen sollen dann im Post-Processing für die Generierung der virtuellen Modelle herangezogen werden. Dieses Projektziel erfordert eine sehr geringe Trajektoriendynamik, damit die Aufnahmen keine Bewegungsunschärfe enthalten. Zudem ist die Anforderung an die Genauigkeit der geflogenen Trajektorie sehr hoch. Das dazu entwickelte Führungskonzept ist für diesen automatischen Abflug von Wegpunkten des eingesetzten Luftschiffs entwickelt worden. Bei dem hier ausgewählten Ansatz geht man vom Aufbau klar abgegrenzter funktioneller Prozesse und Abläufe aus. Der daraus resultierende, hierarchische, funktionsorientierte Architekturansatz ist in Form eines Drei-Ebenen-Architekturmodells realisiert. Die Modellbildung des Luftschiffes erfolgt als starrer Körper mit konstanter Masse sowie Trägheit. Das von Kämpf [15] übernommene Modell, mit modifiziertem Leitwerk auf ein Lambda Leitwerk, berücksichtigt in der Impulsbilanz keine internen Massenflüsse in den Differentialgleichungen. Vor der Reglerimplementierung wird die Dynamik des ungeregelten Luftschiffes eingehend untersucht. Dabei werden die erzielbaren Leistungen des Fluggerätes ebenso beachtet wie die Stabilitäts- und Steuereigenschaften, da diese die Grundlage für den Regelungsentwurf bilden und bereits a priori die maximal erreichbare Manöverleistung des Gesamtsystems definieren. Für den Reglerentwurf ist es notwendig, Anforderungen aus Sicht des Missionsauftrages zu definieren. Das Ziel ist, sich über die Regelungsziele und die Qualität des gewünschten und geforderten Systems Gedanken zu machen. Diese Wünsche und Anforderungen sowie deren physikalische und technische Einschränkungen und Grenzen müssen aus Sicht des Anwenders so ausführlich formuliert werden, dass sich daraus konkrete, regelungstechnische Beziehungen herleiten lassen. Nach der ausführlichen Beschreibung der Reglersynthese der einzelnen Regelungen und deren regelungstechnischen Analyse wird die Tauglichkeit durch Untersuchung des Verhaltens des geregelten Systems im Nominalfall, mit Modellunsicherheiten und unter Windeinfluss überprüft. Zusätzlich wird zu einem ein sogenannter „Iron-Bird“ als Systemprüfstand aufgebaut, welcher bei Entwicklung, Anpassung und Tests der Flugmissionen und der Systeme des Luftschiffes eingesetzt wird, um damit abschließend den Funktionsnachweis beim Einsatz auf dem realen Versuchsträger ALUSTRA I bei sehr geringer Trajektoriendynamik zu erbringen. Zum Schluss konnte mit einem autonomen Flug des Versuchsträgers ALUSTRA I gezeigt werden, dass das Flugführungskonzept die Anforderungen, die vorgegebene Trajektorie mit hoher Bandbreite und guter Führungsgenauigkeit, erfüllen kann. Die durchgeführte Mission sowohl in der HIL-Umgebung als auch auf dem Versuchsfeld besteht in Anlehnung an die Örtlichkeiten des Versuchsfeldes in Gauting im Freistaat Bayern.The use of UAVs nowadays expands to numerous application areas. The range of applications extends from civilian use, such as search and rescue missions, aerial photography, and industrial monitoring tasks in security management, to military missions, such as reconnaissance, surveillance and combat deployment. As part of the research project ALUSTRA MOEWE, a functional autonomous airship filled with helium has been constructed in order to be employed as a camera platform for 3D modelling of buildings and ground surface. In that scope, flight guidance and control theories were brought together into a comprehensive holistic concept, capable of flying around and over the buildings or landscape respectively, and of delivering images using a digital camera with the image recordings being successively used in post-processing for the generation of virtual models. The project objectives require a flight trajectory of low order dynamics, in order for the recordings to contain no motion blur. Additionally, the requirements in terms of accuracy of the flown trajectory are very high. The guidance concept for this purpose has been based on the automatic deviation of the airship with respect to waypoints. The approach selected here results from structuring based on well-defined functional processes and procedures. The resulting hierarchical, function-oriented architecture approach is realized in the form of a three-level architecture model. The airship is modelled as a rigid body with constant mass and inertia. The model adopted by Kämpf [15], albeit with modified fin based on a lambda fin, takes into account no internal mass flow in the differential equations of the momentum balance. Before the controller implementation, the dynamics of the uncontrolled airship are thoroughly investigated. Herein the attainable performance as well as the stability and control characteristics of the aircraft are considered, as these form the basis for the controller design and a priori define the maximum achievable manoeuvre performance of the overall system. For the controller design, it is necessary to define requirements from the perspective of the Mission objectives. The target is to hence go about the control objectives and the quality of the desired and required system attributes. These desired deliverables and prerequisites as well as their physical and technical constraints and limitations need to be so elaborately formulated, from the user's point of view, on order to deduce concrete control engineering relations. After the detailed description and the respective control engineering analysis for the control synthesis of the various schemes, follows the suitability check through studying of the controlled system’s behaviour in the nominal case, taking into account model uncertainties as well as wind influence. Supplementary to the aforementioned investigations, a so-called "Iron Bird" is built as a system test-rig. The "Iron Bird" is utilised in the development, implementation and testing of the flight missions and the employed systems of the airship, in order to provide conclusive proof of function under very low trajectory dynamics for the prototype ALUSTRA I. Finally, through an autonomous flight of the test vehicle ALUSTRA I, it has been showcased that the flight control concept can satisfy the requirements of the predetermined trajectory with high control-bandwidth and good guidance accuracy. The mission has been executed in both the HIL environment as well as on the proving ground located in the area of the Gauting test field in Bavaria

Adaptive Driving Style Classification through Transfer Learning with Synthetic Oversampling

Driving style classification does not only depend on objective measures such as vehicle speed or acceleration, but is also highly subjective as drivers come with their own definition. From our perspective, the successful implementation of driving style classification in real-world applications requires an adaptive approach that is tuned to each driver individually. Within this work, we propose a transfer learning framework for driving style classification in which we use a previously developed rule-based algorithm for the initialization of the neural network weights and train on limited data. Therefore, we applied various state-of-the-art machine learning methods to ensure robust training. First, we performed heuristic-based feature engineering to enhance generalized feature building in the first layer. We then calibrated our network to be able to use its output as a probabilistic metric and to only give predictions above a predefined neural network confidence. To increase the robustness of the transfer learning in early increments, we used a synthetic oversampling technique. We then performed a holistic hyperparameter optimization in the form of a random grid search, which incorporated the entire learning framework from pretraining to incremental adaption. The final algorithm was then evaluated based on the data of predefined synthetic drivers. Our results showed that, by integrating these various methods, high system-level performance and robustness were met with as little as three new training and validation data samples in each increment

Negative pressure wound therapy: Potential publication bias caused by lack of access to unpublished study results data

<p>Abstract</p> <p>Background</p> <p>Negative pressure wound therapy (NPWT) is widely applied, although the evidence base is weak. Previous reviews on medical interventions have shown that conclusions based on published data alone may no longer hold after consideration of unpublished data. The main objective of this study was to identify unpublished randomised controlled trials (RCTs) on NPWT within the framework of a systematic review.</p> <p>Methods</p> <p>RCTs comparing NPWT with conventional wound therapy were identified using MEDLINE, EMBASE, CINAHL and The Cochrane Library. Every database was searched from inception to May 2005. The search was updated in December 2006. Reference lists of original articles and systematic reviews, as well as congress proceedings and online trial registers, were screened for clues to unpublished RCTs. Manufacturers of NPWT devices and authors of conference abstracts were contacted and asked to provide study information. Trials were considered nonrandomised if concealment of allocation to treatment groups was classified as "inadequate". The study status was classified as "completed", "discontinued", "ongoing" or "unclear". The publication status of completed or discontinued RCTs was classified as "published" if a full-text paper on final study results (completed trials) or interim results (discontinued trials) was available, and "unpublished" if this was not the case. The type of sponsorship was also noted for all trials.</p> <p>Results</p> <p>A total of 28 RCTs referring to at least 2755 planned or analysed patients met the inclusion criteria: 13 RCTs had been completed, 6 had been discontinued, 6 were ongoing, and the status of 3 RCTs was unclear. Full-text papers were available on 30% of patients in the 19 completed or discontinued RCTs (495 analysed patients in 10 published RCTs vs. 1154 planned patients in 9 unpublished RCTs). Most information about conference abstracts and unpublished study information referring to trials that were unpublished at the time these documents were generated was obtained from the manufacturer Kinetic Concepts Inc. (KCI) (19 RCTs), followed by The Cochrane Library (18) and a systematic review (15). We were able to obtain some information on the methods of unpublished RCTs, but results data were either not available or requests for results data were not answered; the results of unpublished RCTs could therefore not be considered in the review. One manufacturer, KCI, sponsored the majority of RCTs (19/28; 68%). The sponsorship of the remaining trials was unclear.</p> <p>Conclusion</p> <p>Multi-source comprehensive searches identify unpublished RCTs. However, lack of access to unpublished study results data raises doubts about the completeness of the evidence base on NPWT.</p

Negative pressure wound therapy for open traumatic wounds

BACKGROUND: Traumatic wounds (wounds caused by injury) range from abrasions and minor skin incisions or tears, to wounds with extensive tissue damage or loss as well as damage to bone and internal organs. Two key types of traumatic wounds considered in this review are those that damage soft tissue only and those that involve a broken bone, that is, open fractures. In some cases these wounds are left open and negative pressure wound therapy (NPWT) is used as a treatment. This medical device involves the application of a wound dressing through which negative pressure is applied and tissue fluid drawn away from the area. The treatment aims to support wound management, to prepare wounds for further surgery, to reduce the risk of infection and potentially to reduce time to healing (with or without surgical intervention). There are no systematic reviews assessing the effectiveness of NPWT for traumatic wounds. OBJECTIVES: To assess the effects of NPWT for treating open traumatic wounds in people managed in any care setting. SEARCH METHODS: In June 2018 we searched the Cochrane Wounds Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE (including In-Process & Other Non-Indexed Citations), Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting. SELECTION CRITERIA: Published and unpublished randomised controlled trials that used NPWT for open traumatic wounds involving either open fractures or soft tissue wounds. Wound healing, wound infection and adverse events were our primary outcomes. DATA COLLECTION AND ANALYSIS: Two review authors independently selected eligible studies, extracted data, carried out a 'Risk of bias' assessment and rated the certainty of the evidence. Data were presented and analysed separately for open fracture wounds and other open traumatic wounds (not involving a broken bone). MAIN RESULTS: Seven RCTs (1377 participants recruited) met the inclusion criteria of this review. Study sample sizes ranged from 40 to 586 participants. One study had three arms, which were all included in the review. Six studies compared NPWT at 125 mmHg with standard care: one of these studies did not report any relevant outcome data. One further study compared NPWT at 75 mmHg with standard care and NPWT 125mmHg with NPWT 75 mmHg.Open fracture wounds (four studies all comparing NPWT 125 mmHg with standard care)One study (460 participants) comparing NPWT 125 mmHg with standard care reported the proportions of wounds healed in each arm. At six weeks there was no clear difference between groups in the number of participants with a healed, open fracture wound: risk ratio (RR) 1.01 (95% confidence interval (CI) 0.81 to 1.27); moderate-certainty evidence, downgraded for imprecision.We pooled data on wound infection from four studies (596 participants). Follow-up varied between studies but was approximately 30 days. On average, it is uncertain whether NPWT at 125 mmHg reduces the risk of wound infection compared with standard care (RR 0.48, 95% CI 0.20 to 1.13; I2 = 56%); very low-certainty evidence downgraded for risk of bias, inconsistency and imprecision.Data from one study shows that there is probably no clear difference in health-related quality of life between participants treated with NPWT 125 mmHg and those treated with standard wound care (EQ-5D utility scores mean difference (MD) -0.01, 95% CI -0.08 to 0.06; 364 participants, moderate-certainty evidence; physical component summary score of the short-form 12 instrument MD -0.50, 95% CI -4.08 to 3.08; 329 participants; low-certainty evidence downgraded for imprecision).Moderate-certainty evidence from one trial (460 participants) suggests that NPWT is unlikely to be a cost-effective treatment for open fractures in the UK. On average, NPWT was more costly and conferred few additional quality-adjusted life years (QALYs) when compared with standard care. The incremental cost-effectiveness ratio was GBP 267,910 and NPWT was shown to be unlikely to be cost effective at a range of cost-per-QALYs thresholds. We downgraded the certainty of the evidence for imprecision.Other open traumatic wounds (two studies, one comparing NPWT 125 mmHg with standard care and a three-arm study comparing NPWT 125 mmHg, NPWT 75 mmHg and standard care)Pooled data from two studies (509 participants) suggests no clear difference in risk of wound infection between open traumatic wounds treated with NPWT at 125 mmHg or standard care (RR 0.61, 95% CI 0.31 to 1.18); low-certainty evidence downgraded for risk of bias and imprecision.One trial with 463 participants compared NPWT at 75 mmHg with standard care and with NPWT at 125 mmHg. Data on wound infection were reported for each comparison. It is uncertain if there is a difference in risk of wound infection between NPWT 75 mmHg and standard care (RR 0.44, 95% CI 0.17 to 1.10; 463 participants) and uncertain if there is a difference in risk of wound infection between NPWT 75 mmHg and 125 mmHg (RR 1.04, 95% CI 0.31 to 3.51; 251 participants. We downgraded the certainty of the evidence for risk of bias and imprecision. AUTHORS' CONCLUSIONS: There is moderate-certainty evidence for no clear difference between NPWT and standard care on the proportion of wounds healed at six weeks for open fracture wounds. There is moderate-certainty evidence that NPWT is not a cost-effective treatment for open fracture wounds. Moderate-certainty evidence means that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. It is uncertain whether there is a difference in risk of wound infection, adverse events, time to closure or coverage surgery, pain or health-related quality of life between NPWT and standard care for any type of open traumatic wound

IWGDF guidance on use of interventions to enhance the healing of chronic ulcers of the foot in diabetes

RecommendationsClean ulcers regularly with clean water or saline, debride them when possible in order to remove debris from the wound surface and dress them with a sterile, inert dressing in order to control excessive exudate and maintain a warm, moist environment in order to promote healing. (GRADE strength of recommendation: strong; quality of evidence: low)In general, remove slough, necrotic tissue and surrounding callus with sharp debridement in preference to other methods, taking relative contraindications such as severe ischemia into account. (strong; low)Select dressings principally on the basis of exudate control, comfort and cost. (strong; low)Do not use antimicrobial dressings with the goal of improving wound healing or preventing secondary infection. (strong; moderate)Consider the use of systemic hyperbaric oxygen therapy, even though further blinded and randomized trials are required to confirm its cost‐effectiveness, as well as to identify the population most likely to benefit from its use. (weak; moderate)Topical negative pressure wound therapy may be considered in post‐operative wounds even though the effectiveness and cost‐effectiveness of the approach remain to be established. (weak; moderate)Do not select agents reported to improve wound healing by altering the biology of the wound, including growth factors, bioengineered skin products and gases, in preference to accepted standards of good quality care. (strong; low)Do not select agents reported to have an impact on wound healing through alteration of the physical environment, including through the use of electricity, magnetism, ultrasound and shockwaves, in preference to accepted standards of good quality care. (strong; low)Do not select systemic treatments reported to improve wound healing, including drugs and herbal therapies, in preference to accepted standards of good quality care. (strong; low

Case series: Rapidly growing squamous cell carcinoma after cutaneous surgical intervention

The development of squamous cell carcinoma in sites of split skin graft harvest is a rare complication with only 12 documented cases in the literature. The growth of squamous cell carcinoma after arterial puncture is a rarer phenomenon, with no previous cases documented. This series describes two cases. The first case is of a 70-year-old male who developed rapidly growing squamous cell carcinoma in a graft donor site, 9 weeks after split skin graft repair of pretibial squamous cell carcinoma excision. The second case is of an 84-year-old male who developed a large exophytic squamous cell carcinoma in the right wrist that developed 5 months after radial artery puncture. This case series explores the various mechanisms of de-novo squamous cell carcinoma development in areas of cutaneous surgical intervention, including graft harvest. It also provides recommendations regarding the necessary precautions to avoid implantation of squamous cell carcinoma into distant sites. Lastly it highlights the importance of surveillance for any suspicious lesions arising from areas of previous cutaneous surgical intervention

Flow field characteristics in multiphase airlift systems

The characteristics of the two-phase flow in the riser tube of airlift pumps of short length were investigated. Measurements of the water flow rate as a function of air flow rate for various operating conditions were performed. The air flow rate was varied between 1.8 and 57 m³/h, the submergence ratio between 0.2 and 0.7 and the riser tube lengths investigated were 1.2, 2.4 and 3.1 m. For the investigation of the two-phase flow structure, visual observations in conjunction with simultaneous pressure and conductivity measurements were performed. The visual observations were carried out using high speed video cameras. For the pressure and conductivity measurements high response pressure transducers and point conductivity probes were used. Both probes were placed at various positions along the riser tube. It was found that there are differences in the flow structure between the two-phase flow in the riser tube of the airlift pump and a typical upward two-phase flow in a vertical tube. There are also differences regarding the transitions between the various flow pattern regions for the two flows. These differences are mainly due to the different forces acting on the two flows. From the pressure and conductivity signals the void fraction and pressure distribution along the riser tube for various operating conditions of the airlift pump were computed, while in the slug flow region characteristic quantities like mean velocity and length of the liquid slugs were calculated. The pressure distribution and the water flow rate for various operating conditions were compared with existing models.Ερευνήθηκαν τα χαρακτηριστικά της διφασικής ροής στον αγωγό ανύψωσης ανυψωτικών αεραντλιών (airlift pumps) μικρού μήκους. Έγιναν μετρήσεις παροχής νερού ως συνάρτηση της παροχής του αέρα για διάφορες συνθήκες λειτουργίας. Η παροχή του αέρα μεταβλήθηκε στην περιοχή μεταξύ 1.8 και 57 m³/h, ο λόγος βύθισης μεταξύ 0.2 και 0.7 και τα μήκη του αγωγού ανύψωσης που εξετάστηκαν ήταν 1.2, 2.4 και 3.1 m. Για τη διερεύνηση της δομής της διφασικής ροής έγιναν οπτικές παρατηρήσεις σε συνδυασμό με μετρήσεις πίεσης και αγωγιμότητας. Για τις οπτικές παρατηρήσεις χρησιμοποιήθηκαν βιντεοκάμερες υψηλής ταχύτητας. Για τις μετρήσεις πίεσης χρησιμοποιήθηκαν μεταλλάκτες πίεσης υψηλής απόκρισης, ενώ για τις μετρήσεις αγωγιμότητας χρησιμοποιήθηκαν αγωγιμομετρικοί αισθητήρες. Και τα δύο αισθητήρια τοποθετήθηκαν σε διάφορες θέσεις κατά μήκος του αγωγού ανύψωσης. Από τις μετρήσεις διαπιστώθηκε ότι υπάρχουν διαφορές στη δομή της ροής μεταξύ της διφασικής ροής στον αγωγό ανύψωσης της ανυψωτικής αεραντλίας και μιας τυπικής ανοδικής διφασικής ροής σε κατακόρυφο αγωγό. Επίσης υπάρχουν διαφορές μεταξύ των δύο ροών σε ότι αφορά τις μεταβάσεις μεταξύ των διαφόρων περιοχών όπου επικρατούν τα διάφορα πρότυπα διφασικής ροής. Αυτές οι διαφορές οφείλονται κύρια στις διαφορετικές δυνάμεις που ενεργούν στις δύο περιπτώσεις ροής. Από τα σήματα πίεσης και αγωγιμότητας υπολογίστηκε το κλάσμα κενού και η κατανομή της πίεσης κατά μήκος του αγωγού ανύψωσης, ενώ στην περιοχή της διαλείπουσας ροής υπολογίστηκαν χαρακτηριστικά μεγέθη όπως η μέση ταχύτητα και το μέσο μήκος των υγρών ώσεων. Η κατανομή της πίεσης κατά μήκος του αγωγού ανύψωσης καθώς και η παροχή του νερού για διάφορες συνθήκες λειτουργίας συγκρίθηκαν με υπάρχοντα μοντέλα πρόβλεψης

Enhancement of Pressurizer Safety Valve Operability by Seating Design Improvement

Operating conditions specific to pressurizer safety valves (PSVs) Introduction Pressurizer safety valves (PSVs) are pressure relief devices which provide overpressure protection to the reactor coolant system (RCS ). The PSVs ensure that the system design pressure is not exceeded by opening at a licensed popping pressure with a ±1 percent tolerance. The original design for installation of PSVs was direct mounting on the pressurizer with no loop seal. High PSV leakage due to hydrogen cutting of the seats was experienced in operating plants and led to the incorporation of an ambient temperature water loop seal into the design. As a result of the TMI accident, the industry was required to analyze and design the discharge piping to withstand the transient loading associated with passing the loop seal water volume through the PSVs. Some plants adopted a heated loop seal to allow the loop seal water to flash to steam as it passed through the PSV nozzle to reduce loading in the discharge piping. However, heated loop seal raised the PSV operating temperatures and consequently the PSV nozzle loading. The PSVs addressed in this paper are spring-loaded, selfactuated Crosby type 6M6 with cast body and standard disk insert operating with a heated loop seal. The loop seal profile, similar to EPRI Test 917, is described by The Crosby valve design is susceptible to weak seating induced by