Static Torsion Testing and Modeling of a Variable Thickness Hybrid Composite Bull Gear

Torsional strength of a variable thickness hybrid gear web was measured by performing static testing on the part in a large torsion test frame. The outer rim of the hybrid gear web was fixed to the bottom of the test frame and loading was applied to the web through a shaft. The test setup included the installation of digital image correlation (DIC) systems to obtain deformation and strain measurements from the surfaces of the hybrid gear web and the mechanical test equipment to ensure reliability of the test. The results indicated that the variable thickness hybrid gear web achieved approximately twice the torsional strength compared to that of previous hybrid gear designs. The DIC analysis showed significantly more straining of the loading shaft than the actual test article. Additionally, the results demonstrated the importance and affect that the metallic, lobed interlock features had on the principal strain and out-of-plane displacement fields. The analysis revealed that the fixed outer rim was in fact rotating and a rigid body motion compensation (RBMC) function was computed to determine the actual rotation of the hub and composite web relative to the outer rim. Modeling simulations were performed for the variable thickness hybrid gear web and correlated well with the RBMC rotational deformation seen in the DIC analysis. In addition to benchmarking the load capacity of the hybrid gear web, measuring its strength is useful information to define the parameters needed for dynamic, endurance, and other testing of the part

Evaluation of a Variable Thickness Hybrid Composite Bull Gear

For several years, NASA Glenn Research Center and the U.S. Army Research Laboratory have been investigating hybrid (composite/steel) gear technology for use in vertical lift drive systems. The hybrid gear concept replaces the structural portion of a gear between the shaft and the gear rim with a lightweight carbon fiber composite, in an effort to reduce the overall weight of a gear and increase the drive system power density. Past research includes both small-scale and large-scale hybrid gear concepts, all of which have a constant composite thickness throughout. The design described in this paper is of a variable thickness, such that the composite is thickest at the inner diameter and this thickness is gradually reduced toward the outer diameter. The resulting "stair stepped" design stems from dropping plies of the braided carbon fiber prepreg composite fabric gradually with increased radius. Additionally, the interlock pattern at the inner metallic adapter was adjusted slightly from previous designs to obtain a better stress distribution on the inner metallic adapter. The manufactured variable thickness web was tested both in static torsion tests and operationally in a relevant gearbox environment. The results of these experiments will be presented and compared to a baseline steel configuration

A framework for the simulation of structural software evolution

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2008 ACM.As functionality is added to an aging piece of software, its original design and structure will tend to erode. This can lead to high coupling, low cohesion and other undesirable effects associated with spaghetti architectures. The underlying forces that cause such degradation have been the subject of much research. However, progress in this field is slow, as its complexity makes it difficult to isolate the causal flows leading to these effects. This is further complicated by the difficulty of generating enough empirical data, in sufficient quantity, and attributing such data to specific points in the causal chain. This article describes a framework for simulating the structural evolution of software. A complete simulation model is built by incrementally adding modules to the framework, each of which contributes an individual evolutionary effect. These effects are then combined to form a multifaceted simulation that evolves a fictitious code base in a manner approximating real-world behavior. We describe the underlying principles and structures of our framework from a theoretical and user perspective; a validation of a simple set of evolutionary parameters is then provided and three empirical software studies generated from open-source software (OSS) are used to support claims and generated results. The research illustrates how simulation can be used to investigate a complex and under-researched area of the development cycle. It also shows the value of incorporating certain human traits into a simulation—factors that, in real-world system development, can significantly influence evolutionary structures

Unlocking legal validity. Some remarks on the artificial ontology of law

Following Kelsen’s influential theory of law, the concept of validity has been used in the literature to refer to different properties of law (such as existence, membership, bindingness, and more) and so it is inherently ambiguous. More importantly, Kelsen’s equivalence between the existence and the validity of law prevents us from accounting satisfactorily for relevant aspects of our current legal practices, such as the phenomenon of ‘unlawful law’. This chapter addresses this ambiguity to argue that the most important function of the concept of validity is constituting the complex ontological paradigm of modern law as an institutional-normative practice. In this sense validity is an artificial ontological status that supervenes on that of existence of legal norms, thus allowing law to regulate its own creation and creating the logical space for the occurrence of ‘unlawful law’. This function, I argue in the last part, is crucial to understanding the relationship between the ontological and epistemic dimensions of the objectivity of law. For given the necessary practice-independence of legal norms, it is the epistemic accessibility of their creation that enables the law to fulfill its general action-guiding (and thus coordinating) function

Longitudinal stability of asthma characteristics and biomarkers from the Airways Disease Endotyping for Personalized Therapeutics (ADEPT) study

BACKGROUND: Asthma is a biologically heterogeneous disease and development of novel therapeutics requires understanding of pathophysiologic phenotypes. There is uncertainty regarding the stability of clinical characteristics and biomarkers in asthma over time. This report presents the longitudinal stability over 12 months of clinical characteristics and clinically accessible biomarkers from ADEPT. METHODS: Mild, moderate, and severe asthma subjects were assessed at 5 visits over 12 months. Assessments included patient questionnaires, spirometry, bronchodilator reversibility, fractional exhaled nitric oxide (FENO), and biomarkers measured in induced sputum. RESULTS: Mild (n = 52), moderate (n = 55), and severe (n = 51) asthma cohorts were enrolled from North America and Western Europe. For all clinical characteristics and biomarkers, group mean data showed no significant change from visit to visit. However, individual data showed considerable variability. FEV1/FVC ratio showed excellent reproducibility while pre-bronchodilator FEV1 and FVC were only moderately reproducible. Of note bronchodilator FEV1 reversibility showed low reproducibility, with the nonreversible phenotype much more reproducible than the reversible phenotype. The 7-item asthma control questionnaire (ACQ7) demonstrated moderate reproducibility for the combined asthma cohorts, but the uncontrolled asthma phenotype (ACQ7 > 1.5) was inconstant in mild and moderate asthma but stable in severe asthma. FENO demonstrated good reproducibility, with the FENO-low phenotype (FENO < 35 ppb) more stable than the FENO-high phenotype (FENO ≥ 35 ppb). Induced sputum inflammatory phenotypes showed marked variability across the 3 sputum samples taken over 6 months. CONCLUSIONS: The ADEPT cohort showed group stability, individual stability in some parameters e.g. low FEV1/FVC ratio, and low FENO, but marked individual variability in other clinical characteristics and biomarkers e.g. type-2 biomarkers over 12 months. This variability is possibly related to seasonal variations in climate and allergen exposure, medication changes and acute exacerbations. The implications for patient selection strategies based on clinical biomarkers may be considerable

Phase II study of bi-weekly administration of paclitaxel and cisplatin in patients with advanced oesophageal cancer

In a phase I study we demonstrated the feasibility of a bi-weekly combination of paclitaxel 180 mg m−2 with cisplatin 60 mg m−2. In this study we further assessed toxicity and efficacy of this schedule in the treatment of advanced cancer of the oesophagus or the gastro-oesophageal junction. Patients received paclitaxel 180 mg m−2 administered over 3 h followed by a 3-h infusion of cisplatin 60 mg m−2. Patients were retreated every 2 weeks unless granulocytes were <0.75×109 or platelets <75×109. Patients were evaluated after three and six cycles and responding patients received a maximum of eight cycles. Fifty-one patients were enrolled into the study. The median age was 56 years (range 32–78). WHO performance status were: 0 (19 patients); 1 (29 patients); 2 (three patients). All patients received at least three cycles of chemotherapy and all were evaluable for toxicity and response. Haematological toxicity consisted of uncomplicated neutropenia grade 3 in 39% and grade 4 in 31% of patients. Five patients (10%) were hospitalised, three patients because of treatment related complications and two patients because of infections without neutropenia. Sensory neurotoxicity was the predominant non-haematological toxicity; grade 1 and 2 neurotoxicity was observed in 43 and 20% of patients, respectively. Response evaluation in 51 patients with measurable disease: complete response 4%, partial response 39%, stable disease 43% and progressive disease in 14% of the patients. The median duration of response was 8 months. The median survival for all patients was 9 (range 2–29+) months and the one-year survival rate was 43%. Four patients who received additional local treatment (two patients surgery and two patients radiotherapy) are still disease free after a follow-up of 20–29 months. This bi-weekly treatment of paclitaxel and cisplatin is well tolerated by patients with advanced oesophageal cancer. The toxicity profile of this regimen compares favourable to that of previously used cisplatin- and paclitaxel-based regimens. Trials are underway evaluating this bi-weekly regimen in a neo-adjuvant setting

THE CONCEPT OF LAW AND EFFICACY

Jedno od značenja izraza ‘učinkovitost’ odnosi se na činjenicu da se adresati pravnih normi stvarno ponašaju onako kako to od njih zahtijevaju pravne norme. To se značenje izraza obično koristi u filozofskopravnim raspravama glede toga je li učinkovitost bitan element pojma prava. Prema pravnom pozitivizmu, učinkovitost je u nekim slučajevima i na određene načine uvjet važenja (vrijeđenja) pravnih normi i pravnih sustava. S druge strane, pravni je realizam sklon potpunom poistovjećivanju pravnog važenja s učinkovitosti ili njegovu svođenju na učinkovitost. Prema tome, u oba je filozofskopravna pravca učinkovitost u pravilu uključena u oblikovanje njihovih pojmova prava. Međutim, dok pravnopozitivističko shvaćanje ne utječe na najuobičajenije značenje važenja pravne norme (pripadanje pravne norme pravnom sustavu), a utvrđivanjem učinkovitosti kao kriterija postojanja pravnog sustava ne dodaje mnogo objašnjenju pojma prava, pravnorealističko se shvaćanje suočava s ozbiljnim prigovorima glede svoje objašnjavalačke prikladnosti.One of the senses of the term ‘efficacy’ refers to the fact that norm-addresses actually behave as is required of them by legal norms. This sense of the term is one which is generally used within the jurisprudential discussions about whether efficacy is the essential element of the concept of law. According to legal positivism, efficacy is in some cases and in certain ways the condition of legal validity of both legal norms and legal systems. On the other hand, legal realism tends to entirely identify legal validity or reduce it to efficacy. Thus, in both jurisprudential approaches, efficacy tends to play a role in shaping their respective concepts of law. However, while the legal positivistic view does not affect the most standard sense of legal validity of the legal norm (i.e. the legal norms’ membership in the legal system), and does not add much to the explanation of the concept of law by identifying efficacy as the criterion of legal systems’ existence, the legal realistic view is faced with some serious objections regarding its explanatory adequacy

Hybrid Gear Performance Under Loss-of-Lubrication Conditions

Hybrid composite gear technology is being investigated to increase power density in rotorcraft drive systems. These gears differ from conventional steel gears in that the structural web material is replaced with a lightweight carbon fiber composite. Past studies have focused on performance of this technology under normal operating conditions, however, for this technology to be viable it must also withstand adverse conditions. The study presented here evaluates the performance of hybrid gears under loss-of-lubrication conditions in NASA Glenn Research Centers Contact Fatigue Test Facility. Two experiments are presented using small-scale 3.5 inch (8.9 cm) pitch diameter hybrid gears and compared to a baseline steel gear pair. Results of these tests show that there are limitations to the use of a hexagonal interlock pattern between the steel and composite. There is also evidence that the presence of polymer in the gear during an oil out event has a potential to increase time to failure. Further studies are planned to expand on these initial findings