Vitamin allowance of cosmonauts during preflight training and after completing short space flights

Supply of the main and doubling crews of cosmonauts with vitamins C, A, D, E, B1, B2, B6, PP, and B12, folic acid and carotinoids was studied during training and after the completion of short-term space flights (from 4 to 13 days). As the result of the investigation conducted during the intensive training, 1 month before the space flight some cases of certain vitamins deficiency were revealed. Administration of additional vitamins during 2 weeks before the flight led to a rise in the cosmonauts' supply with vitamins. The findings obtained after the short-term space flights evidence an intensive metabolization of vitamins and increased vitamin requirements during this period.     

Stability of imperfect conical shells with helical reinforcement

The article explains a method of numerical calculation of the stability of imperfect conical shells with helical reinforcement under uniform external pressure. It also investigates the effect of the amplitude of local initial imperfections on the critical loads.Translated from Problemy Prochnosti, No. 12, pp. 67–69, December, 1991.     

Scientific co-operation in Europe and the citation of multinationally authored papers

Under the sponsorship of the U.S. National Science Foundation, CHI Research, Inc. developed the bibliometric indicators for the U.S. National Science Board'sScience Indicators Reports starting withScience Indicators 1972. In the work reported here, for the Commission of the European Communities, CHI has extended the Science Indicators techniques and database to a study of publication, coauthorship and citation within 28 scientific fields related to various European Community programs.Perhaps the most important finding of the research was that internationally coauthored papers — papers authored by scientists affiliated with institutions in more than one EC country — were cited two times as highly as papers authored by scientists working at a single institution within a single country. These EC-EC internationally coauthored papers were cited as highly as EC-Non EC and Non-EC papers. This indicates that the internationally linked European science is of as high impact as any other science in the world.A second key finding was that, after compensating for national scientific size, the degree of international coauthorship did not appear to be particularly dependent upon size. However, linguistic and cultural factors were found to be very strong. The patterns of coauthorship amongst the European countries are far from homogeneous, and are quite heavily affected by linguistic, historical, and cultural factors.Finally, it was found that international coauthorship is increasing steadily, both within and outside of the Community, with some evidence that international cooperation is increasing more rapidly in scientific fields that have been targeted by the Commission.This work has been sponsored by the MONITOR programme of the Commission of the European Communities.     

Effects of flux enhancing polymer on the characteristics of sludge in membrane bioreactor process.

A newly developed membrane performance enhancer (MPE) was used to prevent membrane fouling in a membrane bioreactor (MBR) process. It transpired that 1,000 mg/l of MPE reduced polysaccharide levels from 41 mg/I to 21 mg/I on average under the experimental condition. Repeated experiments also confirmed that 50-1,000 mg/l of MPE could reduce membrane fouling significantly and increase the intervals between membrane cleanings. Depending on MPE dosages and experimental conditions, trans-membrane pressure (TMP) increase was suppressed for 20-30 days, while baseline TMP surged within a few days. In addition, MPE allowed MBR operation even at 50,000 mg/l of total solid and reduced permeate COD. However, no evidence of toxicity for sludge was found from respiratory works.     

Vibratory drier for the chemical industry

Modern designs are examined, and technical data presented for vibratory electric and convection driers, driers with infra-red sources, and steam driers.     

Auditory motivated level-crossing approach to instantaneous frequency estimation

We address the problem of estimating the instantaneous frequency (IF) of a phase signal using its level-crossing (LC) information based on front-end auditory processing motivation. We show that the problem of IF estimation using LC information can be cast in the framework of estimation from irregularly sampled data. The formulation has the generality of estimating different types of IF without the need for a quasistationary assumption. We consider two types of IF-polynomial and bandlimited; we use polynomial interpolating functions for the former, and for the latter, we propose a novel "line plus sum of sines" model. The model parameters are estimated by linear regression. Considering the noisy case, LC data for different levels is analyzed, and methods for combining different estimators from LCs are discussed. Theoretical and extensive simulation results show that the performance of the zero-crossing (ZC) based IF estimator and the level-crossing based IF estimator with smaller level values is better than those obtained with higher level values or their combinations. The new technique reaches the Crame/spl acute/r-Rao bound (CRB) roughly above 4 dB signal-to-noise ratio (SNR), and its performance does not deteriorate rapidly with mismatch in the IF order compared with the other techniques in the literature.     

Performance comparison of space-time block coded and cyclic delay diversity MC-CDMA systems

Spatial diversity is a widely applied technique for enhancing wireless system performance since it greatly reduces the detrimental effects of multipath fading. Space-time block codes have been considered the best choice for transmit diversity in narrowband environments, but their use in broadband channels is questionable due to their inability to pick up multipath diversity. However, when used in conjunction with an MC-CDMA system, they achieve not only full spatial but also variable multipath diversity depending on the employed spreading. In comparison, cyclic delay diversity is an attractive approach to achieve spatial and multipath diversity. Its simplicity and conformability with current standards makes it desirable for multicarrier systems. Previous studies suggest that CDD is only advantageous with an outer channel code for OFDM systems. In this article, we compare STBCs and CDD applied to an MC-CDMA system in terms of complexity and performance. It is shown that for an MC-CDMA system, CDD benefits from spreading and channel coding that makes it very competitive with STBCs, particularly since it is applicable to any number of transmit antennas with no loss in rate.