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991.
Brd Bakkejord Jan B. Hyer 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》1995,10(2)
The Civil Aviation Administration of Norway (NCAA) is currently undertaking a comprehensive programme for the modernization and enhancement of air traffic control services in southeast Norway. The most important element within this programme is the establishment of a new Air Traffic Control Centre (ATCC) for Oslo that will provide both area and approach control services within the area. A national air traffic control school (the ATS Academy), which will provide both basic and advanced training for air traffic controllers, will be established in conjunction with the ATCC. The facility will also provide for maintenance, development and testing of application software and system enhancements. The ATCC is sited underground, and administration and training facilities are in buildings outside, connected to the air traffic control centre by a tunnel. The paper describes the major operation systems and sub-systems that will support the ATCC activities. 相似文献
992.
Ehlers-Danlos syndrome (EDS) is a heterogeneous group of connective tissue disorders. Recently mutations have been found in the genes for type V collagen in a small number of people with the most common forms of EDS, types I and II. Here we characterise a COL5A2 mutation in an EDS II family. Cultured dermal fibroblasts obtained from an affected subject synthesised abnormal type V collagen. Haplotype analysis excluded COL5A1 but was concordant with COL5A2 as the disease locus. The entire open reading frame of the COL5A2 cDNA was directly sequenced and a single base mutation detected. It substituted a glycine residue within the triple helical domain (G934R) of alpha2(V) collagen, typical of the dominant negative changes in other collagens, which cause various other inherited connective tissue disorders. All three affected family members possessed the single base change, which was absent in 50 normal chromosomes. 相似文献
993.
The purpose of our work is to control the interfacial bonds between PVC and NBR using the ammonium salts of triazine thiols and dithiodimorpholine (DTDM) and thereby reveal the relation between the interfacial bonds and the final mechanical properties of products. In the experimental work a two-stage process was used. At first, an NBR/PVC blend was mixed with a mono-tetra-n-butylammonium salt of triazine trithiol at a temperature of 100°C on a two-roll mill to give the branching structure of triazine thiols into PVC. In the second stage branched NBR/PVC reacted with DTDM to afford the branched PVC containing trithiomorphonyl groups. In the presence of ZnO at 160°C trithiomorphonyl groups react with NBR to form a crosslinking structure between NBR and PVC. The mechanical properties of cured NBR/PVC blends were markedly improved by the treatment process and after addition of tetramethylthiuram monosulphide also. The mechanical properties were not improved by increasing the concentration of TT-TBA (tetrabutylammonium salt of 1,3,5-triazine-2,4,6-trithiol) over 4.2 phr. 相似文献
994.
Cheng-Geng Jan Ruey-Beei Wu Powen Ilsu Dau-Chyrh Chang 《Antennas and Propagation, IEEE Transactions on》1996,44(8):1120-1126
A novel analysis for computing the admittance characteristics of edge slots with a salient feature in successfully considering the finite waveguide wall thickness is presented. The variational equation for the electric field in the slot region between the inner and outer waveguide walls is derived by applying the variational reaction theory and solved by the finite-element method. The division of the slot region into small elements of triangular cylinders and the basis function for each element are described in detail. In the limiting case of zero wall thickness, this finite-element analysis is reduced to a moment-method analysis using Galerkin's approach with triangular basis functions. The effects of waveguide wall thickness on the characteristics of the slot are investigated by comparing the numerical results with and without considering the wall thickness. Negligence of the wall thickness may result in a severe underestimation of the resonant length by as large as 14% for edge slots cut in typical X-band waveguides. The computed results with the finite wall thickness taken into account have been checked with the measured data published in previous literature and those obtained by a carefully devised experimental setup. Good agreement between theoretical and experimental results is obtained to demonstrate the validity of the analysis 相似文献
995.
The melting of secondary-phase particles—or, more precisely, the melting of such particles together with the surrounding matrix—in
two ternary Al-Mg-Si alloys has been studied. In the quasi-binary Al-Mg2Si alloy, one melting reaction is found. In the alloy with an Si content in excess of that necessary to form Mg2Si, three different melting reactions are observed. At upquenching temperatures above the eutectic temperature, the reaction
rates are very high, and it is assumed that they are controlled by diffusion of the alloying elements in the liquid. Melting
is also observed after prolonged annealing at temperatures below the eutectic temperature in these alloys, which is explained
by the different diffusion rates of Mg and Si. The rate of the melting reaction is in this case assumed to be controlled by
diffusion of the alloying elements in the solid α-Al phase. It is shown that calculation of the particle/matrix interface
composition, which determines when melting is possible, cannot be made solely on the basis of the phase diagram, but must
also include the rate of diffusion of Mg and Si. The melting temperatures observed differ somewhat from the accepted eutectic
temperatures for these alloys. On prolonged annealing, the liquid droplets formed dissolve into the surrounding matrix and
their chemical composition is found to change during dissolution. The resulting eutectic structure after quenching of a droplet
is explained by the phase diagram and the different diffusion rates of Mg and Si as well as by the nucleation conditions of
the constituents involved. 相似文献
996.
Postterm pregnancy remains constantly a difficult and controversial problem in modern obstetrics. The aim of this study is to discuss the definition of the postterm pregnancy, complications for both the foetus (macrosomia associated with birth trauma and shoulder dystocia, oligohydramnios, meconium aspiration, postmaturity syndrome) and mother (increase rate of caesarean births). We discussed also the antepartum surveillance and the management of the postterm gestation (time and way of delivery). The management of postterm pregnancy should be individualised and based on the above findings. Treatment includes active methods (induction of labour, elective caesarean section) or conservative way (strict foetal antenatal surveillance). 相似文献
997.
We describe a female stillbirth with duplication of 3q21-->qter and deletion of 11q23-->qter resulting from an unbalanced segregation of a maternal t(3;11) reciprocal translocation. The proband had some of the clinical features consistent with those seen in patients with dup(3q) syndrome or distal del(11q) syndrome. Prenatal sonographic examination showed short limbs, intrauterine growth retardation, and an omphalocele containing the liver. 相似文献
998.
The effects of glyceryl nonivamide (GLNVA) on ionic currents were compared and examined in rat pituitary GH3 cells. Hyperpolarization-activated K+ currents in GH3 cells bathed in high-K+ Ca2+-free external solution were studied to assess effects of GLNVA on the an inwardly rectifying K+ current (I(K(IR))). GLNVA is very potent in blocking I(K(IR)) in a concentration-dependent manner, with a half maximal concentrations of 0.1 microM. The complete block of I(K(IR)) achieved with concentrations > or = 1 microM revealed the presence of a non-inactivating current. We also found that GLNVA at a concentration above 30 microM inhibited L-type voltage-dependent Ca2+ current and two components of K+ outward currents, while GLNVA (< or = 3 microM) did not have any effect on them. This study shows that GLNVA, in addition to retaining the capability of eliciting peptidergic neurons, is a selective block of I(K(IR)) in GH3 cells and will provide a useful tool for characterizing I(K(IR)) and understanding its physiological function. In addition, the carefulness should be taken about the interpretation of GLNVA-mediated responses in vivo or in vitro. 相似文献
999.
Wouter A. Serdijn Albert C. Van Der Woerd Jan Davidse Arthur H. M. Van Roermund 《Analog Integrated Circuits and Signal Processing》1995,8(2):131-143
This paper discusses the design of low-voltage low-power fully-integratable automatic gain controls. Four different AGCs are presented, all consisting of three elementary building blocks: a controlled amplifier, a comparator and a voltage follower. Their design is treated separately. As an example, the final section describes an automatic gain control for hearing instruments, realized in a bipolar process. 相似文献
1000.
Jan Pejtersen 《Indoor air》1996,6(4):239-248
Abstract The sensory pollution load and microbial contamination of glass-fibre filters at high and low relative humidity were investigated in an experimental set-up in the laboratory. Dust and particles from the outdoor air were collected in two EU7 glass-fibre filters for a pre-conditioning period of 16–18 weeks during which there was a constant airflow with a velocity of 1.9 m/s through the filters. One of the filters was exposed to outdoor air of approximately 40% relative humidity and 10°C, the other to outdoor air of approximately 80% relative humidity and 5°C. The dust in ventilation filters can constitute a serious pollution source in the indoor environment, causing deterioration in the quality of the supply air even before it enters the ventilated spaces. The sensory pollution load from the used filters after the continuous operating time of 16–18 weeks was significantly higher than the sensory pollution load from new filters but the sensory load at 40% and 80% relative humidity did not differ. The microbial contamination of the supply air downstream of the filters, which on average had been exposed to outdoor air of 40% and 80% relative humidity, was negligible. 相似文献