Integrated development of CFRP structures for a topless high performance vehicle

When modern saloon cars are re-engineered as convertibles (or roadsters) it is typical for them to lose 50% or more of the body’s torsional rigidity. Consequently the vehicles rarely handle quite as crisply, nor do they ride as well as the coupes from which they derived. This paper highlights the fundamental contributions of advanced composites in achieving the desired value of handling of the Murcièlago Roadster without penalizing the overall weight of the vehicle. To compensate for the absence of the roof structure, the vehicle was strongly redesigned by introducing new structural members and reinforcing existing critical components. A new all-carbon/epoxy composite sub-frame, which spans the entire engine bay, is comprised of elliptical tubular members, and it is the first of its kind in a production vehicle. Engineering of the sub-frame, from preliminary design to manufacturing decisions, is the focus of this paper, and is achieved through a Building Block approach that sets the program within the Integrated Product Development (IPD) strategy that the Advanced Composites Division of Automobili Lamborghini S.p.A. employs for its technology demonstrators. The strategy consists in a concurrent analytical and experimental development of the product, from the initial conceptual design and coupon testing, through the stages of element and subcomponent engineering, to final component manufacturing.     

Wavelength stabilizer for telecommunication lasers: design and optimization

We introduce a novel method for the wavelength stabilization of semiconductor lasers for telecommunications. The approach is based on a wavelength-sensitive photodetector which, in a feedback system, generates an error signal apt to tune the source to the desired value. We extensively investigate the influence of various design parameters on performance figures such as tunability, steady-state error, and temperature dependence, as well as fabrication tolerances. The results are compared with standard specifications for wavelength-division-multiplexed optical communications with various channel spacings.     

Metastatic oligodendroglioma. Case report

We report a case of remote metastasis of oligodendroglioma. Similar cases are reported in the literature for malignant cerebral tumors. Our case seems rather different because of low grade histology. Potential malignancy was evidenced only by further investigations with labeling indexes.     

Bond strengths of toluenes, anilines, and phenols: to hammett or not

The Hammett equation correlates the effects of Y on many different chemical properties of YC(6)H(4)ZX families of compounds. One of the most surprising is that the Z-X bond dissociation enthalpy (BDE), a homolytic property, can be correlated for some 4-YC(6)H(4)ZX families with electrophilic substituent constants, sigma(p)(+)(Y), which were largely derived from the rates of the heterolytic S(N)1 solvolyses of para-substituted cumyl chlorides. Although there is no Hammett correlation of the C-X BDEs in 4-YC(6)H(4)CH(2)X (X = H, halide, OPh) families, there are good correlations of N-X BDEs with sigma(p)(+)(Y) in 4-YC(6)H(4)NHX (X = H, CH(3), OH, F) and excellent correlations of O-X BDEs with sigma(p)(+)(Y) in 4-YC(6)H(4)OX (X = H, CH(3), CH(2)Ph) families. The reasons for this varied behavior are discussed.     

Removal of fulvic acid from aqueous media by adsorption onto modified vermiculite

Clay minerals are low cost materials that can be structurally modified and exploited for removal of natural organic matter from freshwaters. The present study shows that vermiculites modified by ion exchange with hexadecyltrimethylammonium or intercalation with poly(hydroxy iron) cations are potential adsorbents for removal of fulvic acid, whereas the adsorption on the raw clay mineral is negligible. The efficiency of the modified vermiculite was evaluated by measuring adsorption isotherms by the batch technique using initial fulvic acid concentrations between 2.5 and 50.0 mg L^− 1, with one hour of contact time. At least 94% of the fulvic acid initially present in a 20 mg L^− 1 solution was sorbed onto either the intercalated poly(hydroxy iron) cations or the organically modified vermiculite. Up to an initial concentration of 5.0 mg L^− 1 the adsorption is irreversible, and no quantifiable fulvic acid was measured in the desorption experiments. For initial fulvic acid concentrations between 10.0 and 50.0 mg L^− 1, desorption was between 2.3% and 4.9% for Fe(III) intercalated vermiculite, and between 1.4% and 9.2% for the organoclay. The adsorption percentages on intercalated poly(hydroxy iron) cations increased upon lowering pH and increasing the ionic strength, indicating the occurrence of strong binding mechanisms such as ligand exchange. Adsorption percentage of fulvic acid onto the organoclay also increased with lowering of pH, but in this case the adsorption percentages showed a small decrease at high ionic strength, suggesting that electrostatic attraction plays an important role in the adsorption process.     

Social movement documentary practices: digital storytelling,social media and organizing

ABSTRACT

Scholars and activists have studied social movement media for its potential to challenge dominant narratives, build community relationships and create social change. This paper presents a case study of two short-form documentary projects with Black Lives Matter 5280 and the Service Employees International Union, Local 105 in Denver, Colorado to explore how collaborative media-making projects assist in building local grassroots campaigns of racial and economic justice. The communication strategies as well as the distribution efforts via online social networks and community screenings are discussed in order to analyse how documentaries rely upon personal narratives to animate members and allies’ feelings and then connect them with traditional forms of organizing like community meetings and public demonstrations. The participatory aspects of filmmaking are viewed through democratic theory, which emphasizes the social relations of citizenship and shared communal values over material and cultural resources, rather than visual aesthetics or technical processes.     

A short term −12° head down tilt does not mimic microgravity in terms of human gonadal function

A significant reversible decrease in testosterone (T) has been associated with microgravity in male rodents and humans. Urinary T excretion increases in primates under hypergravity. Hypogonadism is somehow related to abnormally high levels of leptin (L), a hormone produced by the adipose tissue which has been found to increase under microgravity simulation conditions like head down bed rest (HDBR). The aim of this study was to assess hemodynamic and pituitary-adrenal and -gonadal adaptation to an acute HDBR test to be eventually used on a routine basis to get better prepared to next space flights. The Authors performed a 1 hour ?12° HDBR in 6 male and 6 female volunteers who underwent heart rate and blood pressure measurement together with a blood draw three times at 30 min intervals from the start to the end of the test for L, T, estradiol (E₂), LH, androstenedione (A), cortisol (F), ACTH. 12 age- and sexmatched control subjects followed the same protocol except for keeping the sitting position all the time. According to the ANOVA for repeated measures, no changes occurred in L, T, E₂ or LH whereas A, F and ACTH significantly decreased independently of gender. During HDBR systolic blood pressure decreased in both genders, diastolic blood pressure decreased significantly only in men and HR showed a more clear-cut decrease in women than in men. As a conclusion, such an acute steep-slope HDBR protocol may be efficiently used to testing immediate individual haemodynamic or adrenal response to microgravity but is not suitable for studies concerning gonadal adaptation.     

宽带数字单边带下变频器

数字单边带下变频器是软件无线电中不可缺少的组成部分,也是射电观测中,数据采集设备的重要组成部分,由于该模块紧接高速A/D采样器之后,所以对其运算处理能力有很高的要求.本文提出了实现宽带数字单边带下变频器的一种可行方案——并行处理,可以从根本上解决数字信号处理的瓶颈效应.