Sealed Space Research Articles

Multi-mode radiator panels

The invention relates to a system with multi-mode radiator panels used to reproduce sound. The multi-mode radiator panels include at least one driver, a core layer and two cover layers connected to the core layer. The panels are typically mounted in a frame with attachments providing a connection between the frame and the unit formed of the core layer and the cover layers. To protect the system against overload and damage, the entire driver electronics is housed in a hermetically sealed air space located between the frame, the core layer and the attachments. The driver electronics includes a power amplifier powered by low-voltage power supply. The voltage supply may be buffered by a battery to keep the average power supplied to the electronics small, while still being able to reproduce infrequently occurring peak power events. Buffering of the battery has the additional advantage that if the power supply is completely interrupted, the battery enables the sound reproduction to continue for a certain time in the event of a power failure, which is important for transmitting emergency announcements. The multi-mode radiator panels can also be connected via a bus, so that a single cable strand may be used to supply the acoustic signal and the electric power.

Portable communication device with collapsible speaker enclosure

A portable communication device includes a speaker enclosure having a speaker and a plurality of telescoping nested shells moveable between a collapsed configuration and an expanded configuration. The shells have a top and bottom surface and interlocking sidewalls such that when the enclosure is deployed into an expanded configuration the shells form a rigid enclosure with a substantially sealed acoustic space therein. The space tunes an acoustic compliance for the speaker so as to improve broadband frequency response whether the communication device is using a privacy or speakerphone mode of operation.

Deactivation of Hydrodesulfurization Catalysts in Two-stage Resid Desulfurization Process. (Part 4). Deactivation in a Long-term Aging Test under Constant Reaction Temperature.

The long-term aging tests involving hydrodesulfurization catalysts were done at 380°C. The used catalysts were then characterized to investigate the deactivation mechanism. The amount of coke on the catalyst peaked around 30 days, and then decreased. This decrease in coke was due to the hydrogenation reaction with Ni-sulfide deposited on the catalyst. Elemental analysis, measurement of pore size distribution, and activity tests of the used catalysts revealed that the catalyst deactivation at start and middle of a run (MOR) was caused by coke and by metal deposits, respectively. In addition, calculations revealed plugging of pore mouths and the presence of sealed space of pores at MOR, resulting in the catalyst deactivation.

Deactivation of Hydrodesulfurization Catalysts in Two-stage Resid Desulfurization Process. (Part 6). Characterization and Activity of Used Hydrodesulfurization Catalysts.

The activity tests of used HDS catalysts, which were prepared during 30 days of aging under various HDS reaction conditions, were performed and their characterization was performed to understand the initial deactivation of the HDS catalysts. The pore volume measurements revealed that the sealed space of pore increased with aging, resulting in HDS catalyst deactivation. Laser Raman and 13C-NMR analysis showed that aromaticity of coke was the highest at the center of the catalyst pellet and was influenced more by reaction temperature than by reaction pressure. Comparison of HDS activity of the used catalysts with real feed to that with a model compound (thiophene) showed that the effect of reactant diffusion on HDS activity was negligible. A good correlation was observed between HDS activity and coke content, suggesting that coke deactivation was predominant at the start of run, regardless of HDS reaction conditions involved.

5814731 Ultrasonic scanning apparatus for nondestructive site characterization of structures using a planar based acoustic transmitter and receiver in a rolling pond

The invention is a carriage type sonic or ultrasonic testing apparatus for flaw and deterioration detection testing in a structure, especially concrete. The apparatus detects both location and type of flaw in a structure. The carriage unit incorporates a rolling pond feature which includes: i) foam-covered tracks and rollers, this soft foam material in addition to its primary function prevents vibration of the transducers while traversing rough surfaces such as weathered concrete. The tracks and rollers form a water-tight seal with each other and the specimen surface; ii) an air-removal brush assembly which maintains contact with a specimen surface to facilitate transmission and reception of ultrasonic energy into and out of a test specimen; iii) an ultrasonic isolator element and optional wave absorbers; and iv) the ultrasonic transducer suspension system. A transducer water bed is continuously maintained while the system is in motion across the concrete. A sealed space surrounds the transducer system, and that space is continuously flooded with water so as to keep the bottom sections of the transducers submerged. This sealed space continuously transports a sufficient amount of fluid (water) along the concrete surface for proper acoustic coupling. The ultrasonic transducer includes a granite wedge as an impedance-matching transducer faceplate material for concrete structural examinations.

Tear film-contact lens interactions.

Contemporary contact lenses, when considered in perspective, are remarkably effective; the remaining primary challenge, however, appears to be the relationship of the contact lens to the tear film. The number of contact lens wearers in the United States is no longer increasing, perhaps the result of discomfort which may occur initially, preventing contact lens wear, or which may develop over a period of years, resulting in termination of wear. Contemporary lenses can usually provide comfort if tear film integrity can be maintained. The environmental humidity is a critical component in the formation and thickness of the lipid layer for both the preocular and the prelens tear films, thus influencing tear film stability and evaporation. A common clinical observation is the gradual development of discomfort over 10 or more years of contact lens wear by patients who initially are totally asymptomatic. This discomfort, probably the result of compromise to the tear film occurring with age, frequently leads to discontinuation of contact lens wear. Intermittent discontinuation of contact lens wear may also occur as the result of seasonal discomfort when the relative humidity is low, or when the nature of the visual demand, as in extended VDT operation, inhibits blinking. The fragile tear film and its relation to contact lenses is readily understood by two quotations: "The human tear film is rather unstable, but it is regenerated by frequent blinking", and "When a contact lens is placed in the eye, the lens alters the normal structure of the tear film and affects its rate of evaporation.(ABSTRACT TRUNCATED AT 250 WORDS)

Reliability of n-CdS/p-CdTe solar modules in accelerated environmental tests and effect of oxygen

Abstract The reliability under various severe environmental conditions was investigated in n-CdS/p-CdTe solar modules that contained air and an oxygen-releasing agent inside a sealed space between the glass substrate and the back sheet of the module. The modules were stable in an 80°C test, an 80°C–90% relative humidity test, a 10-cycle heat shock test and a temperature-and-humidity cycle test but were unstable in a weather meter (dew cycle) test. A kneed point was observed in the degradation curve when relative output power was plotted against test period for the weather meter test. It was thought that the modules became unstable when the concentration of oxygen in the sealed space exceeded 2 vol.%.

Life-Span of Insulating Glass Units

This article from the Swedish National Testing Institute describes the new test method adopted as part of a certification programme for insulating glass units. It measures the water vapour transmission into the sealed air space and compares it to the capacity of the desiccant in the unit. The water vapour transmission is measured indirectly by two successive measurements of the dewpoint temperature inside the air space. Before the test starts the desiccant is removed in order to detect small differences in the amount of water vapour in the unit. A theoretical life span of the unit is then calculated assuming 10.0 g/m3 as the average water vapour concentration to which it will be exposed in practice. Proposed requirement for the test is a theoretical life of one hundred years for the unit.

Effects of duration of exposure to ethylene on dormancy release in freesia corms

The exposure of freesia corms to ethylene (C 2H 4) at ca. 10 μl/l air for only 5 h was sufficient to promote sprouting, either under a closed system in which corms were treated in a sealed space of 3–10 1 or under a flow system in which corms were exposed to a continuous flow of air containing C 2H 4. Under the closed system, little change in corm response to C 2H 4 was found with increasing duration of exposure from 5 to 48 h, and the C0 2 concentration reached nearly 4% after 48 h. On the other hand, under the flow system, in which CO 2 did not accumulate above 0.1%, the promotive effect of C 2H 4 was diminished by extended exposure from 5 to 48 h. Repeated treatment with C 2H 4 for 23 h daily on 4 successive days resulted in the lowering of the promotive effect as compared with a single treatment, but repeated application of C 2H 4 for 5 h daily showed the same effect as a single application and gave a high sprouting rate similar to smoke treatment, independent of ambient temperature ranging from 25 to 35° C. Corms exposed to C 2H 4 for 5 h daily, or to smoke for 4 days, exhibited a better chilling response and advanced flowering.

Life support system with autonomous control employing plant photosynthesis

This research was aimed at obtaining a closed control system. This was achieved by placing all the technological processes providing for human vital activities within the hermetically sealed space, and by transferring the entire control and guidance of these processes to people inhabiting the system. In contrast to existing biological life support systems, man has been included not only as a participant of metabolism, but as an operator who is the central figure in collecting information, making decisions and controlling all technological processes. To tackle this problem, the “BIOS-3” experimental complex was created for performing long-term experiments using different structures of biological life-support system. The experiment lasted six months and consisted of three stages. During the first stage the system was comprised of two equivalent phytotrons with the culture of wheat and an assortment of vegetable plants, and the living compartment. At the second stage, one of the phytotrons was removed while a compartment of chlorella cultivators was introduced. The third stage differed from the second, the former using wheat phytotron and the latter employing phytotron with an assortment of vegetable cultures. Three men inhabited the system simultaneously. The experiment demonstrated that a biological life support system controlled autonomously from the inside is feasible within a small confined space. However, immunological and microbiological research shows, that the medium created by the system is not fully adequate for man. In conclusion, some prospects have been outlined for further studies of biological life support systems.

Unimpaired Infectivity of the Nematode Haemonchus contortus after Freezing for 44 Weeks in the Presence of Liquid Nitrogen

Exsheathed larvae of Haemonchus contortus were frozen over liquid nitrogen, and were kept frozen for 44 weeks. Upon thawing, the larvae showed no loss in viability as judged by motility. Their infectivity to sheep was compared with that of normal larvae (ensheathed and nonfrozen). Sheep given 1,500 frozen exsheathed larvae acquired worm counts (688 to 921, mean 722) similar to those given normal larvae (439 to 852, mean 627). It has been reported from this laboratory that exsheathment of the infective larva of the nematode Haemonchus contortus enables it to withstand freezing in the presence of liquid nitrogen (Campbell et al., 1972). When that report was prepared for publication the longest survival time recorded was 4 weeks; and although the larvae had been shown to be highly infective, it had not then been possible to make a critical comparison of the infectivity of frozen and nonfrozen larvae in worm-free sheep. The present study shows that frozen larvae remain viable (without perceptible loss in numbers) for at least 44 weeks and that their infectivity is unimpaired. MATERIALS AND METHODS Use was made of a strain of H. contortus originating on Branchburg Farm, New Jersey, and maintained by serial passage in sheep for many years. Larvae were harvested from conventional fecal cultures after 7 days' development at 27 C and approximately 90% relative humidity. The larvae of this strain can readily be exsheathed by bubbling carbon dioxide into the suspension of larvae, followed by agitation at 37 C; and this was the method employed for exsheathment. The larvae were concentrated in "Vitro" brand 1-dram screw-cap vials (Wheaton Glass Company, Milville, New Jersey). Each vial contained roughly 150,000 larvae in 1 ml water. They were frozen by transferring the vials directly from air at room temperature to the storage section of a liquid nitrogen container (Union Carbide Corporation, Model Designation Linde LD-40). According to the manufacturer of the unit, the temperature in this sealed space would not be more than 96 C higher than the temperature of the underlying liquid nitrogen (-196 C). The vapor space contained 4 layers of steel storage drawers; the vials were stored in the second layer from the top, but we Received for publication 20 October 1972. have no reason to believe that the exact location was a critical factor. The larvae were thawed by immersing them in water at about 55 C, allowing approximately 300 ml of water per vial, and making no attempt to maintain the initial temperature of the bath. As soon as the contents of the vial were thawed, the larval suspension was diluted several-fold with water at room temperature and allowed to stand at room temperature for 1 hr before the motility was assessed. The lambs used in the infectivity trial had been raised on slatted floors which were cleaned daily, and were kept under these conditions throughout the experiment. They were known to harbor light infections of Capillaria, Strongyloides, and Eimeria spp. at the time of use, but were not passing trichostrongyle eggs in the feces. The lambs were of both sexes and were approximately 3 months old. At necropsy the abomasum was removed and the contents collected on a 200-mesh sieve (pore size 0.074 mm). The contents were stained with iodine and examined in their entirety to determine the total number of worms present. The abomasum was allowed to soak in saline at 37 C for 24 to 48 hr, with the addition of an antibiotic preparation to suppress putrefaction. The resultant material was collected on a 200-mesh screen, stained, and examined in its entirety for worms. EXPERIMENTS AND RESULTS Larvae of H. contortus were exsheathed and frozen on 25 August 1971. A sample of these larvae, henceforth designated "frozen" larvae, was removed from the container on 28 June 1972, that is, after 44 weeks in the frozen state. After thawing, examination of 200 larvae under a stereoscopic microscope revealed that 92% of them were motile. It is possible that an even greater percentage of the larvae in this culture would have been motile prior to freezing; but the motility of 88% of the larvae in the nonfrozen control culture (below) is

Corrosive Effect of Plastics, Rubber and Wood on Metals in Confined Spaces

AbstractThe corrosion of metals enclosed in equipment or packages is influenced by vapours arising from other materials which may also be present. Plastics, wood and rubber are the principal sources of such vapours. Even when no vapours are evolved, corrosion of a metal may result from contact with some non-metallic materials.Samples of iron, zinc, copper, aluminium and cadmium either in contact with or in a sealed space with various types of non-metallic material, were exposed to corrosion. The extent of corrosion was observed and analyses were made of products and of the surrounding atmosphere. Formic and acetic acid are the most aggressive volatile products from wood and the same compounds, together with formaldehyde, ammonia and halogen acids, may be evolved from plastics and sulphur compounds from rubber. Of the plastics, phenolic resins, especially as mouldings filled with wood flour, and, of the woods, oak, chestnut and beech are the most likely to produce acetic and formic acid vapours, but other ...

Functional state of the vestibular system of man kept in a hermetically sealed space for 120 days

Estimation was made of the threshold sensitivity and reactivity (cupulometry) of the vestibular analyzer in persons who had stayed in a hermetically sealed chamber during 120 days. It was found that under these conditions functional changes occurred in the main in the central part of the analyzer and were manifested by a decrease in its reactivity.

Development of Hydrogen Porosimeter

The absolute porosity of a rock or sand may be defined as the volume of the inter particle space expressed as a percentage of the total rock volume. The effective porosity as contrasted with the absolute porosity is the volume of the interparticle spaces which intercommunicate with passages of sufficientsize to permit the entrance or recovery of gas or oil, also expressed as apercentage of the total rock volume. A knowledge of effective porosity is ofprime importance in estimating the ultimate recovery to be expected from oiland gas-bearing formations. The determination of the effective porosity of a rock includes the measurementof two values:the volume of the rock as a whole, andthe volume of thegrains and sealed pore space. This paper deals with a new apparatus which hasbeen called a "hydrogen porosimeter" for determining the volume of thegrains and the sealed pore space. This volume is determined by means of thepressure relations established in the instrument by the introduction of a knownquantity of hydrogen. The Hydrogen Porosimeter The apparatus used in this work consists of an upper chamber for measuring thegas, a lower chamber for holding the sample to be tested, a gage for measuringthe pressures, a tank of hydrogen, and the necessary connections. (Figs. 1 and 2.) Of the several gases that might be used for this work, hydrogen has been chosenfor three reasons:it deviates less from the gas laws than most gases;it readily penetrates the sample;it is absorbed less than most gases bythe solids and liquids with which it may come in contact. Method of Operation After placing the sample to be tested in the lower chamber, the apparatus isthoroughly flushed with hydrogen to remove all air from the system, which isthen brought to atmospheric pressure The valve connecting the two chambers isnext closed and the pressure in the upper chamber is brought up to a pressureby admitting gas from the tank.