A model to compare performance of space and ground network support of low-Earth orbiters

This article compares the downlink performance in a gross average sense between space and ground network support of low-Earth orbiters. The purpose is to assess what the demand for DSN support of future small, low-cost missions might be, if data storage for spacecraft becomes reliable enough and small enough to support the storage requirements needed to enable support only a fraction of the time. It is shown that the link advantage of the DSN over space reception in an average sense is enormous for low-Earth orbiters. The much shorter distances needed to communicate with the ground network more than make up for the speedup in data rate needed to compensate for the short contact times with the DSN that low-Earth orbiters have. The result is that more and more requests for DSN-only support of low-Earth orbiters can be expected

Application of the statistical theory of extreme values to spacecraft receivers

Statistical theory of extreme values application to spacecraft communication receiver

Kontrola bolesti uzrokovanih udisanjem prašine u keramičkoj industriji u Velikoj Britaniji

The British ceramic industry has always been concentrated in a small area of Staffordshire. Because of the widespread use of flint (almost 100% free silicic acid) for kiln placing and as a component of most ceramic articles, silicosis has been a serious health problem for about 300 years. The paper deals with the trends of silicosis morbidity since the reconstruction of the industry which began at the end of the last war. In only a few processes hazardous materials have been substituted by harmless ones (for instance flint by alumina in the placing of bone china). Most efforts have been concentrated on the improvement of local dust control and general workshop hygiene. In recent years it was found that the traditional so-called protective clothing of ceramic workers constituted itself a definite hazard and has now been replaced by materials made of dust-repelling man-made fibres. Modified routine mass radiography has proved a valuable tool for assessing the incidence of dust disease in ceramic workers and the analysis of its records suggests that only a small proportion of workers acquired pneumoconiosis during the past 15 years. Although manufacture of flint-containing articles must be considered the most hazardous risk, it is shown that pneumoconiosis occurs to a significant extent in the manufacture of fine china which does not contain any flint. In recent years the most impressive facet of pneumoconiosis statistics has been the rapidly declining rate of progressive massive fibrosis. In Great Britain category I simple pneumoconiosis (according to the I. L. 0. classification) is generally and not considered to be a »disease process« but its importance as a biological index of undue dust exposure is stressed.U radu se prikazuju rezultati koji su postignuti u suzbijanju bolesti pluća uzrokovanih udisanjem prašine u industriji keramike i porculana u Engleskoj. Ta je industrija od davnine bila koncentrirana na malom području Staffordshirea. Zbog proširene upotrebe kremena (gotovo 100% slobodni silicijev dioksid) kao jedne od sirovina za proizvodnju većine proizvoda, kao i njegove primjene u fazi obrade nekih proizvoda (posipanje predmeta od »bone china« kremenom prije unošenja u peći), silikoza je predstavljala vrlo ozbiljan zdravstveni problem u toj industriji kroz gotovo 300 godina. Ukazujući na izvanredan uspjeh koji je u rješavanju toga problema postignut od rata do danas, autor nas upoznaje s mjerama koje su u tu svrhu poduzimane. Zanimljivo je da je samo u nekim slučajevima izvršena zamjena štetnog materijala neškodljivim (npr. kremen je zamijenjen aluminijem pri obradi - pečenje proizvoda od »bone china«), najviše je napora uloženo u poboljšanje kontrole lokalnih izvora zaprašenja i unapređenje općih higijenskih prilika u radnoj okolini. U najnovije vrijeme uvedena su posebna radna odijela izrađena od plastične mase koja ne sakupljaju prašinu, jer se ustanovilo da su klasični platneni ogrtači predstavljali značajan izvor za-prašenja. Autor ističe da se u kontroli bolesti uzrokovanih udisanjem prašine pokazala vrlo prikladnom modificirana metoda rutinske fluorografije. Podaci pokazuju da je za posljednjih 15 godina samo mali dio uposlenih obolio od pneumokonioze. Premda je, nema sumnje, najopasnija ekspozicija kremenu, pokazalo se da od pneumokonioze mogu odoljeti i radnici koji rade u proizvodnji »china« porculana, gdje se kremen sada uopće ne upotrebljava. Svakako najznačajnija zdravstvena karakteristika zabilježena posljednjih godina u ovoj industriji jest naglo smanjenje broja pneumokonioza s progresivnom masivnom fibrozom. Autor napominje da se u Vel. Britaniji jednostavni oblik pneumokonioze (prema klasifikaciji Međunarodnog biroa rada) još ne smatra oboljenjem. Međutim, to je važan biološki indeks aktuelne ekspozicije prašini

A note on the wideband Gaussian broadcast channel

It is well known that for the Gaussian broadcast channel, timeshared coding is not as efficient as more sophisticated broadcast coding strategies. However, the relative advantage of broadcast coding over timeshared coding is shown to be small if the signal-to-noise ratios of both receivers are small. One surprising consequence of this is that for the wideband Gaussian broadcast channel, which is defined, broadcast coding offers no advantage over timeshared coding at all, and so timeshared coding is optimal

A simple model for DSS-14 outage times

A model is proposed to describe DSS-14 outage times. Discrepancy Reporting System outage data for the period from January 1986 through September 1988 are used to estimate the parameters of the model. The model provides a probability distribution for the duration of outages, which agrees well with observed data. The model depends only on a small number of parameters, and has some heuristic justification. This shows that the Discrepancy Reporting System in the Deep Space Network (DSN) can be used to estimate the probability of extended outages in spite of the discrepancy reports ending when the pass ends. The probability of an outage extending beyond the end of a pass is estimated as around 5 percent

The New Market for Federal Judicial Law Clerks

In the past, judges have often hired applicants for judicial clerkships as early as the beginning of the second year of law school for positions commencing approximately two years down the road. In the new hiring regime for federal judicial law clerks, by contrast, judges are exhorted to follow a set of start dates for considering and hiring applicants during the fall of the third year of law school. Using the same general methodology as we employed in a study of the market for federal judicial law clerks conducted in 1998-2000, we have broadly surveyed both federal appellate judges and law students about their experiences of the new market for law clerks. This paper analyzes our findings within the prevailing economic framework for studying markets with tendencies toward "early" hiring. Our data make clear that the movement of the clerkship market back to the third year of law school is highly valued by judges, but we also find that a strong majority of the judges responding to our surveys has concluded that nonadherence to the specified start dates is very substantial -- a conclusion we are able to corroborate with specific quantitative data from both judge and student surveys. The consistent experience of a wide range of other markets suggests that such nonadherence in the law clerk market will lead to either a reversion to very early hiring or the use of a centralized matching system such as that used for medical residencies. We suggest, however, potential avenues by which the clerkship market could stabilize at something like its present pattern of mixed adherence and nonadherence, thereby avoiding the complete abandonment of the current system.

Data compressor Patent

Description of system for recording and reading out data related to distribution of occurrence of plurality of event

The Telecommunications and Data Acquisition Report

This publication, one of a series formerly titled The Deep Space Network Progress Report, documents DSN progress in flight project support, tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations. In addition, developments in Earth-based radio technology as applied to geodynamics, astrophysics and the radio search for extraterrestrial intelligence are reported

Phase-locked loop with sideband rejecting properties Patent

Phase locked loop with sideband rejecting properties in continuous wave tracking rada