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Experimental work was carried out to study the effect of surface enhancement on the crystallization fouling in a double pipe heat exchanger under forced convective heat transfer. The experiments were performed using a hot fluid (salt solution) that had a temperature of 40 °C and Reynolds number range between Re h = 5300 and 20,000. The normal solubility salt (sodium sulfate, Na 2 SO 4 ) was used at its saturation concentration. The temperature of the cold fluid (distilled water) was 10 °C and Reynolds number (Re c ) range was between 13,000 and 22,000. The cold fluid was pumped through the inner tube and the hot fluid was pumped counter currently through the outer tube. This caused the sodium sulfate to precipitate on the outside surface of the tube. The impact of scale fouling on the heat transfer coefficient and fouling resistance was investigated for both a smooth and an enhanced surface. The effect of surface enhancement on the fouling process was studied by installing a coiled wire insert on the inside or outside surface of the inner tube. The results revealed that the surface enhancement increased the heat transfer rate by 150%–80% depending on Re h and Re c . In addition, it significantly decreased the fouling resistance (R f ). It was found that installing the coiled wire insert onto the outer surface of the inner tube is more effective in reducing fouling resistance than installing it on the inside surface of the inner tube. At low Re c and Re h , the surface enhancement is more effective in reducing fouling than at higher Re c and Re h . The reduction in fouling resistance due to the surface enhancement was up to 86% at low Re c and Re h and 46% at high Re c and Re h .

This paper describes an adaptive quarter wave tube used to attenuate a tone from the exhaust noise of a large diesel engine. A sliding-Goertzel algorithm was used to calculate the phase angle of the transfer function between a microphone in the adaptive quarter wave tube and in the main exhaust duct. The control system adjusted the length of the adaptive quarter wave tube until the phase angle was 90 and caused the sound pressure level at the cylinder ring frequency in the exhaust duct to be minimized. The system was able to adapt to changes in engine speed, exhaust gas temperature, and load applied to the engine. The results demonstrate that the sliding-Goertzel algorithm can be used eectively to estimate the phase angle in an adaptive

It is well known that the acoustic performance of silencing elements decreases with an increase in exhaust gas flow. Tests were conducted on three orifice geometries of side-branches on an adaptive quarter-wave tube to determine which was the least compromised by the high-speed exhaust gas passing over the side-branch. The side-branch geometries that were tested were a sharp edge, a backward inclined branch, and a bell mouth. The experimental results show that the side-branch with a bell-mouth geometry resulted in the greatest noise reduction by an adaptive quarter-wave tube.

Crystallization fouling experiments were performed in a channel for a cross flow of hot saturated sodium sulphate (Na 2 SO 4 ) solution over a pipe containing cold water. The heat transfer coefficient and fouling thermal resistance were determined from measurements of local surface temperature and the thickness of the crystalline fouling layer. A systematic assessment of the asymptotic variation of these parameters with time was obtained for a range of hot salt solution Reynolds number based on pipe diameter ( Re hD ) of 165–485, salt solution bulk temperature of 30 °C–50 °C, and cold water (at 5 °C) Reynolds number in the pipe ( Re c ) of 7500–25000. It was found that the temperature of the salt solution has a large effect on the fouling rate. Increasing the pipe surface temperature decreases the crystallization fouling rate. Increasing the hot solution Reynolds number, via the velocity, decreases the fouling thermal resistance, while increasing the cold water Reynolds number, via the velocity, decreases the fouling thermal resistance, but at the same time it increases the fouling layer thickness. The crystallization process that applies here was found to be under activation control (i.e. chemical kinetic control) so that the mass transport of salt plays only a minor role.

An online monitor has been designed, built, and tested that is capable of measuring the residual transuranic concentrations in processed high-level wastes with a detection limit of 370 Bq/ml (10 nCi/ml) in less than six hours. The monitor measures the (α,n) neutrons in the presence of gamma-ray fields up to 1 Sv/h (100 R/h). The optimum design was determined by Monte Carlo modeling and then tempered with practical engineering and cost considerations. A multiplicity counter is used in data acquisition to reject the large fraction of coincident and highly variable cosmic-ray-engendered background events and results in an S/N ratio ~1.

Substituted 3-amino-2-hydroxyamides and related hydroxyamides and acylhydrazines were identified as inhibitors of human methionine aminopeptidase-2 (MetAP2). Examination of substituents through parallel synthesis and iterative structure-based design allowed the identification of potent inhibitors with good selectivity against MetAP1. Diacylhydrazine 3t (A-357300) was identified as an analogue displaying inhibition of methionine processing and cellular proliferation in human microvascular endothelial cells (HMVEC).

A field test of a complicated statically indeterminate floor system on a historic steel truss bridge has been conducted to obtain a more accurate load rating of the structure than possible using calculated predic­ tions of wheel load distributions. The empirically determined wheel load distributions resulted in the identifi­ cation of the floor system, particularly the transverse floor beams, as the element governing the load rating of the structure. Favorable lateral distribution of wheel loads among the stringers by a glued laminated treated timber deck was noted. The experimental determination of wheel load distributions has provided an inexpensive means of intelligently allocating limited county resources for the maintenance and rehabilitation of an inventory of aging bridges.

The authors initiated a closed-ended group for inmates in Patuxent Institution, a maximum security correctionalfacility located in Jessup, Maryland. This group was designed to provide aformat, by which inmates could examine and discuss a series of moral dilemmas in the Kohlbergian tradition, as well as provide a vehicle by which the authors could assess the level of moral judgment employed by the group members. Based on this experience, it was determined that the participants' moral judgments essentially reflected Stage 2 thinking, the stage often referred to as Instrumental Relativism. Furthermore, the analysis showed that a significant correlation existed between the inmates'stage of moral development and recorded institutional infractions, a general measure of institutional adjustment. The present essay summarizes observations related to the nature of these moral judgments made by the inmate participants and speculates on the interrelationship of these judgments to past criminality and institutional adjustment.

Scintillator materials are widely used for the detection of ionizing radiation in a variety of applications including high energy and nuclear physics, astrophysics, geophysical exploration, medical imaging, security inspection, and industry. Research involving the use of photoluminescence, radioluminescence, thermoluminescence, and synchrotron radiation is underway to further our fundamental understanding of the factors affecting scintillator performance and to discover improved materials. The importance of defects and their effects on energy transfer and overall scintillation efficiency are illustrated by considering recent results for cerium-activated crystals and glasses.

Epithermal/thermal boron neutron-capture therapy (BNCT) is a promising treatment method for malignant tumors. Because the doses and dose rates for medical therapeutic radiation are very close to the normal tissue tolerance, small errors in radiation delivery can result in harmful overdoses. A substantial need exists for a device that will monitor, in real time, the radiation dose being delivered to a patient. Pacific Northwest Laboratory (PNL) has developed a scintillating glass optical fiber that is sensitive to thermal neutrons. The small size of the fibers offers the possibility of in vivo dose monitoring at several points within the radiation field. The count rate of such detectors may approach 10 MHz because the lifetime of the cerium activator is fast. Fluxes typical of those in BNCT (i.e., 10/sup 9/ n/cm/sup 2//sec) may be measured with a single fiber because of this potentially high count rate and the small diameter of the fiber. >

Fingerling diploid (mean ± SD: 63 ± 14 g) and triploid (45 ± 17 g) channel catfish (Ictalurus punctatus) were stocked into 0.04-hectare earthen ponds at a density of 11,000 fish/hectare, with three replicate ponds for each ploidy level. Fish were fed a pelleted commercial catfish ration (32% protein) to satiation daily. Ponds were drained and fish harvested after 185 d. No significant differences were found between diploid and triploid catfish for harvest weight and dress-out percentage; however, triploids had significantly (P < 0.05) lower survival and yield, and higher feed conversion (weight of feed fed/weight gain) than diploids. Macroscopic examination of gonads revealed the expected lack of sexual development and gonadal maturation in triploids.

Kringle 5, a proteolytic fragment of human plasminogen has been shown to potently inhibit angiogenesis. The tetrapeptide KLYD derived from kringle 5 has been shown to capture many activities of kringle 5 in vitro. Further simplification has been achieved by replacement of the two central amino acids with a 4-aminobenzoic acid spacer group. Molecules displaying the required recognition groups on this core show similar in vitro properties to kringle 5, and are able to displace radiolabeled protein from a high affinity binding site on endothelial cells.

An AR (1) series measured at unit interval is still an AR(1) when measured at another interval h which is a multiple of the original, The autocorrelation at lag 1 for the new series is given by ρ1′ = φ1h. At the α significance level a sample of length n of the process is not distinguishable from white noise whenever $$h \geqslant \ln [1 + n (1 - \phi _1^m )/\chi _{m - 1}^2 ,\alpha l/ - \ln \phi _1^2 $$

A hierarchy of models is being developed to represent the changes in climate that could occur in the next 10,000 years at proposed nuclear waste repository sites in the U.S. Three levels of modeling of the global aspects of climate change are included. At the broadest level a multitude of theoretical representations are being considered, most based upon the Milankovitch theory. A set of at least 150 situations will be examined, and those of concern for site stability will be screened for more thorough analysis at the next level of detail. The screening criteria include estimation of the probability of the event; the level of probability which must be considered (0.0001) requires use of the most detailed paleoclimatic records available. Uncertainty in the results will be evaluated by comparison of model reconstructions to the paleoclimatic record and by Monte Carlo analyses.

Operation Intercept was launched along the United States-Mexico border in September of 1969, ostensibly to halt the flow of marijuana, heroin, and dangerous drugs. In reality, however, it was designed not to interdict narcotics but to publicize the new administration's war on crime and force Mexican compliance with Washington's antidrug campaign. With the exception of border residents, the much-heralded operation has been forgotten by most Americans a decade later. But as President Jimmy Carter discovered during his visit in early 1979, Mexicans, and particularly their presidents, have keen memories. Hastily conceived, unilateral programs such as Operation Intercept go far in explaining why.

Divergence has been computed, from the adiabatic form of the energy equation, for (a) each of 56 locations on a grid covering most of the United States and Canada; (b) each of the 100-mb and 50-mb levels; (c) each twice-daily observing time during the period January 17 to February 14, 1957. The root-mean-square value of divergence, computed for each map, was usually between 2 and 3×10−6 sec−1 at both 100 mb and 50 mb. For most map times and levels, but with important exceptions, the correlation of horizontal convergence and downward motion was positive. A large center of horizontal divergence was apparent in the analyzed area several days before evidence of stratospheric warming was pronounced (about February 4); this was replaced during the time of rapid development of the warming by a large center of horizontal convergence. In general, there was no significant correlation between total divergence and divergence of the geostrophic wind.

Vertical motion has been computed by the adiabatic method for (a) each of ninety locations on a grid covering most of the United States, Canada, and the adjacent North Atlantic region; (b) each of the 100-mb, 50-mb, and 25-mb levels; (c) each twice-daily observing time during the period January 16, 1957, to February 15, 1957. Until the occurrence of rapid warming, the vertical-motion patterns typically showed downward motion west of troughs and upward motion east of troughs. After the beginning of rapid warming (after January 23 at 25 mb and after February 2 at the lower levels), the vertical-motion pattern was characterized by a very large area of uniformly downward motion. Extreme magnitudes of vertical motion were about 8 cm sec−1 at 25 mb, 6 cm sec−1 at 50 mb, and 4 cm sec−1 at 100 mb. These and other results are illustrated by maps showing the distribution of height, temperature, and vertical motion at the three pressure surfaces for four selected map times.

The vertical distribution of ozone over Tallahassee, Florida, is discussed on the basis of 145 observations during the years 1963–1965. There is usually a minimum of ozone density near the tropical tropopause at about 16 km and a single pronounced maximum at about 23 km. The maximum is at a somewhat higher altitude in summer and fall than in winter and spring. About 80% of the ozone is found above 18 km, about 60% between 18 and 30 km.

Ozone distributions in the vertical over Tallahassee, Florida, as measured by the chemiluminescent method, are compared with distributions inferred from Umkehr measurements. The differences are systematic with respect to altitude and probably arise mainly from the particular technique used to deduce ozone distributions from the Umkehr measurements. Variations about the mean according to the two methods show a moderately positive correlation in each of six layers from 250 to 4 mb.

In a recent paper [Kays and Craig, 1965], we evaluated temperature advection V·∇T from the equation V⋅∇T=−(ƒT/g)V2∂θ/∂z((1)) where V is the velocity, T the temperature, ƒ the Coriolis parameter, g the gravity field strength, V the wind speed, and θ the wind direction. Small-scale structure, which is present in the wind field in the upper stratosphere, was eliminated by smoothing V2 and θ separately. Alternatively, one can compute temperature advection from the equation V⋅∇T=−(ƒT/g)(u ∂u/∂z−v ∂u/∂z)((2)) where u is the wind component toward the east and υ the wind component toward the north. In this case, u and υ can be smoothed separately.

A high‐power low‐threshold graded‐index separate confinement heterostructure AlGaAs single quantum well laser on Si substrates has been demonstrated for the first time by a hybrid growth of migration‐enhanced molecular beam epitaxy followed by metalorganic vapor phase epitaxy. The quantum well laser showed an output power of more than 400 mW per facet under pulsed conditions. A room‐temperature threshold current of 300 mA was obtained with a differential quantum efficiency of 40% without facet coating. The threshold current density was 550 A/cm2 for a cavity length of 500 μm. These results show the highest peak power reported to date for low‐threshold lasers on Si substrates. The full width at half maximum of the far‐field pattern parallel to the junction was 6°. Threshold current densities as low as 250 A/cm2 were obtained for lasers on GaAs substrates.

Inversion of the measurements obtained by the infrared limb scanner on the Nimbus 6 satellite has demonstrated that the stratospheric and mesospheric temperatures and ozone concentrations may be obtained remotely from space with accuracy and precision comparable to in situ methods. Such global data have many applications in middle atmospheric research and operational temperature sounding.