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A raster multibeam lithography tool is in Etec’s roadmap to meet the stringent requirements of sub 100 nm mask fabrication. The tool leverages the long experience obtained with the ALTA laser pattern generators and the high resolution capabilities of e-beam lithography. A photocathode controlled by acousto-optic modulated 257nm laser beams is utilized to generate 32 electron beams. The beams are accelerated at 50 KV in an electron column, demagnified and focussed on the mask or wafer substrate. The performance of the photocathode and other system components will be presented together with preliminary lithographic patterning.

This paper explores the addition of frequency-domain transmit antenna arrays to the cyclic-prefix CDMA (CP-CDMA) system concept. CP-CDMA is a novel type of single carrier DS-CDMA that employs OFDM-style cyclic prefixes to facilitate efficient frequency-domain receiver processing in broadband CDMA cellular systems. CP-CDMA is intended for high-bandwidth, high-delay-spread cellular channels, such as those envisioned for systems that evolve from current 3G CDMA standards. This paper examines both single-data stream (i.e., maximal ratio transmission) and multiple data stream (i.e., spatial multiplexing also known as multiple-input, multiple-output or MIMO) techniques for CP-CDMA systems that operate with high code usage and multi-level modulation in broadband high delay-spread channels. In the proposed algorithms, both the transmit and receive array processing is performed completely in the frequency-domain to allow the tracking of frequency-selective MIMO channels. Simulation results are presented to show the efficacy of the proposed methods.

Bell Labs layered space-time (BLAST) promises to increase greatly the capacity of future broadband mobile communications. However, in MIMO communication systems, the decoded BER performance of successive cancellation receivers is limited by the performance of the stream with the highest mean squared error. The paper presents a novel method to determine the different power weighting to be applied by the transmitter to each BLAST data stream in frequency-selective communications to improve the performance of a successive cancellation receiver. In addition, the new method predetermines the successive cancellation decoding order, thus simplifying the receiver. Simulation results for a spread OFDM system show up to a 5.0 dB improvement in frequency-selective channels over BLAST with equal power on each stream.

Semi-blind channel estimators promise to dramatically reduce the number of pilots needed for accurate channel estimation over pilot-only based techniques while providing much better performance than blind algorithms. This paper presents a novel semi-blind multi-user channel estimator for OFDM based on the maximum likelihood estimator. The estimator works by iterating between estimating the channels between multiple transmit antennas and each receive antenna and the respective symbols for each transmitter. Simulation results show that the semi-blind channel estimator is effective even when the frequency-domain pilot spacing is greater than the Nyquist spacing.

This paper explores the addition of antenna diversity schemes to the recently-proposed cyclic-prefix CDMA (CP-CDMA) system concept CP-CDMA is a novel type of single carrier DS-CDMA that employs OFDM-style cyclic prefixes for the purposes of facilitating efficient frequency-domain equalization in broadband CDMA cellular systems. CP-CDMA is intended for high-bandwidth, high-delay-spread cellular channels (especially in the forward link), such as those envisioned for systems that evolve from current 3G CDMA standards. This paper proposes transmit and receive antenna diversity techniques for CP-CDMA systems that operate with high user loading and multi-level modulation in broadband high delay-spread channels. Simulation results show that the proposed transmit diversity technique and receive frequency domain equalization provide vastly superior performance than previous Walsh-code-based transmit diversity methods using RAKE reception.

This paper describes a novel type of single-carrier DS-CDMA system that combines the use of OFDM-style cyclic prefixes with frequency-domain equalization, for use on the forward link of broadband CDMA cellular systems. The proposed method is referred to as CP-CDMA. The combination of cyclic prefixes and MMSE frequency-domain equalization solves many of the performance and complexity problems that arise in CDMA receivers when techniques such as multi-level modulation and full code usage are employed. Simulation results are presented for a 20 MHz system with multi-level modulation and these results are compared to the performance of a conventional CDMA system with either a RAKE receiver or a time-domain equalizer. Results indicate that CP-CDMA provides significantly improved performance, yet has lower complexity than the time-domain equalized system.

This paper summarizes the propagation characteristics of a 20 MHz channel at a carrier frequency of 3.676 GHz transmitted from a two-antenna base to a two-antenna mobile receiver. The experiments were conducted in a moderate density suburban setting outside Chicago, Illinois. The transmit and receive systems are described, as are the data collection procedures and data analysis. The results include path loss measurements and various metrics of the MIMO channel, such as channel impulse responses, rms delay spread, and other spatial characteristics.

The authors have developed a method for inferring articulatory parameters from acoustics. For this method, an X-ray microbeam records the movements of the lower lip, tongue tip and tongue dorsum during normal speech. A neural network is then trained to map from concurrently recorded acoustic data to the articulatory data. The device has applications in speech therapy as a lip-reading aid, and as a basis for other speech technologies including speech and speaker recognition and low data-rate speech transmission. >

The paper introduces a frequency-domain near-maximum likelihood (ML) joint Doppler frequency (DF)/time of arrival (TOA) search for channel characterization. The search is iterative and operates by finding one or more DF/TOA pairs at each step that minimize the channel estimation mean squared error. Because of its excellent ability to estimate frequency-domain channels as well as identify channel parameters (i.e., DFs and TOAs), we call the algorithm CHAMPS (CHannel estimation via an Approximate ML Parameter Search). CHAMPS is used to characterize the channels measured from an experimental 18.775 MHz OFDM mobile system operating at 3.676 GHz. The experimental system was used to collect data in Schaumburg, Illinois, an environment characterized by both industrial and residential areas. Differential delays up to 24 /spl mu/sec were detected as well as Doppler frequencies that are three times the expected Doppler frequency due to reflections off vehicles traveling in the opposite direction as the test van.

We describe a system that automatically identifies the script used in documents stored electronically in image form. The system can learn to distinguish any number of scripts. It develops a set of representative symbols (templates) for each script by clustering textual symbols from a set of training documents and representing each cluster by its centroid. "Textual symbols" include discrete characters in scripts such as Cyrillic, as well as adjoined characters, character fragments, and whole words in connected scripts such as Arabic. To identify a new document's script, the system compares a subset of symbols from the document to each script's templates, screening out rare or unreliable templates, and choosing the script whose templates provide the best match. Our current system, trained on thirteen scripts, correctly identifies all test documents except those printed in fonts that differ markedly from fonts in the training set.

This paper explores strategies for multiple-input/multiple-output (MIMO) communications where the number of data streams is fixed and each stream has the same modulation type. For the fixed data stream case, transmit and receive weights based on the singular value decomposition (SVD) approach may not give the best BER performance. This paper explores two alternate strategies to the SVD approach for jointly calculating the transmit and receive weights based on minimizing the mean-squared error summed over all data streams. The first strategy finds linear transmit and receive weights, and the second strategy finds linear transmit weights and successive cancellation receive weights.

This paper explores the use of quasi-static frequency-domain antenna combining weights for multi-user (e.g., SDMA) or multi-stream (e.g., MIMO) communication systems operating in rapidly time-varying frequency-selective channels. By implementing combining weights that are constant across a time slot but are updated from slot-to-slot (i.e., "quasi-static"), great computational complexity savings can be realized compared to calculating new weights at each data block within a time slot. The quasi-static weights are computed by first modeling, the time-varying channel for each user as the superposition of multiple time-invariant channels, called Doppler channels. The weights are then calculated based on all users' Doppler channels. These new weights work by using some of the degrees of freedom of the antenna array to suppress time variations as well as multiple access interference. Despite being fixed across a time slot, these weights can equalize and suppress SDMA interference even when the channel varies significantly over the slot. Simulation results show the effectiveness of these weights for equalization and interference suppression.

This paper presents two new multi-user techniques that aid in the decision-directed tracking of a rapidly time-varying OFDM channel. The first is based on applying gradient optimization techniques to a least squares multi-user frequency-domain channel estimation problem. The second technique is based on a method for modeling a time-varying frequency response as a linear combination of a small number of time-invariant "Doppler channels." This technique provides a formula for updating these Doppler channels, which greatly improves the performance of decision-directed tracking. These techniques are tested for different decision-directed methods in a simulated 6.0 MHz OFDM system with a 330 Hz maximum Doppler frequency and an 8.0 /spl mu/sec maximum delay spread.

This paper contains a new frequency-domain multi-stream channel estimation technique for communication systems such as MIMO-OFDM. The estimator works by first determining the Time Of Arrivals (TOAs) of each data stream using a near Maximum Likelihood (ML) approach and then solving for the corresponding gains. In addition, this paper presents a training sequence that enables other TOA estimators such as ESPRIT to determine multiple data stream's TOAs. The performance of various channel estimators is compared through simulations and experimental data and the results show that the new TOA estimator has the best overall performance.

Using census data from the Censo Agropecuario 1995-96, the authors map indicators of current land use, and agricultural productivity across Brazil's Legal Amazon, These data permit geographical resolution about ten times finer than afforded by"municipio"data, used in previous studies. The authors focus on the extent, and productivity of pasture, the dominant land use in Amazonia today. Simple tabulations suggest that most agricultural land in Amazonia yields little private economic value. Nearly ninety percent of agricultural land is either devoted to pasture, or has been out of use for more than four years. About forty percent of the currently used pastureland, has a stocking ratio of less that 0.5 cattle per hectare. Tabulations also show a skewed distribution of land ownership: almost half of Amazonian farmland is located in the one percent of properties that contain more than two thousand hectares. Multivariate analyses relate forest conversion, and pasture productivity to precipitation, soil quality, infrastructure, and market access, proximity to past conversion, and protection status. The authors find precipitation to have a strong deterrent effect on agriculture. The probability that land is currently claimed, or used for agriculture, or intensively stocked with cattle, declines substantially with increasing precipitation levels, holding other factors (such as road access) constant. Proxies for land abandonment are also higher in high rainfall areas. Together these findings suggest that the wetter Western Amazon is inhospitable to exploitation for pasture, using current technologies. On the other hand, land conversion, and stocking rates are positively correlated with proximity to past clearing. This suggests that in the areas of active deforestation in eastern Amazonia, the frontier is not :hollow:, and land use intensifies over time. But this area remains a mosaic of lands with higher, and lower potential agricultural value.

The National Institute for Occupational Safety and Health (NIOSH) established its Alaska Field Station in Anchorage in 1991 after identifying Alaska as the highest-risk state for traumatic worker fatalities. Since then, the Field Station, working in collaboration with other agencies, organizations, and individuals, has established a program for occupational injury surveillance in Alaska and formed interagency working groups to address the risk factors leading to occupational death and injury in the state. Collaborative efforts have contributed to reducing crash rates and mortality in Alaska's rapidly expanding helicopter logging industry and have played an important supportive role in the substantial progress made in reducing the mortality rate in Alaska's commercial fishing industry (historically Alaska's and America's most dangerous industry). Alaska experienced a 46% overall decline in work-related acute traumatic injury deaths from 1991 to 1998, a 64% decline in commercial fishing deaths, and a very sharp decline in helicopter logging-related deaths. Extending this regional approach to other parts of the country and applying these strategies to the entire spectrum of occupational injury and disease hazards could have a broad effect on reducing occupational injuries.

Almost 50 per cent of the population in Paraguay is rural and about 90 per cent of the rural population is employed in agriculture (Jazairy et al., 1992). There are indications that the incidence and severity of poverty in rural areas is much worse than in urban areas.

Reassortants possessing the hemagglutinin (HA) gene from A/Equine/London/1416/73 (H7N7) [Eq/Lond] and five or more genes from A/Chicken/Pennsylvania/1370/83 (H5N2) [Ck/Penn] were lethal in chickens. This result demonstrates that horses can maintain influenza viruses whose HAs are capable of promoting virulence. Thus, reassortment of equine and avian influenza virus genes could generate viruses that might be lethal in domestic poultry.

Background. Kivalina is a northwest Alaska barrier island village of 400 people vulnerable to storm surges exacerbated recently by delayed winter sea and shore ice formation. The village has no in-home piped water or sewage; the ‘‘washeteria’’ is the only structure providing public showers, laundry facilities and flush toilets. In October 2004, a storm damaged the washeteria septic system resulting in prolonged facility closures. We assessed rates of gastrointestinal, respiratory and skin infections potentially impacted by prolonged washeteria closures. Methods. We obtained washeteria closure dates from 2003 to July 2009 and defined >7 day closure as prolonged. We received de-identified data on all Kivalina clinic visits from 2003 to 2009 and selected visits with ICD-9 diagnosis codes for respiratory, skin, or gastrointestinal infection; subsequent same patient/same illness-category visits within 14 days were excluded. We compared annual visit rates, for all ages combined, before (2003-2004) and after (2005-2009) the ‘‘2004’’ storm. Results. The washeteria had prolonged closures for 34 days (4.7%) in the 2 years 2003-2004 and 864 days (51.7%) between January 2005 and July 2009. Closures ranged from 8 to 248 days. Respiratory infection rates declined significantly from 1.32 visits/person/year in the 20032004 period to 0.99 visits/person/year in the 2005-2009 period. There was a significant increase in skin infection rates after 2004, peaking at 0.28 visits/person/year in 2007 and then declining significantly to 0.15 visits/person/year in 2009. Gastrointestinal infection rates remained stable and low throughout (average: 0.05 visits/person/year). No temporal association was observed between respiratory, gastrointestinal or skin infection rates and prolonged washeteria closures. Conclusion. The Kivalina washeteria was closed frequently and for extended periods between 2005 and 2009. Initial closures possibly resulted in increased skin infection rates. No increase in respiratory or gastrointestinal infections was noted. Evaluation of community adaptations to closures and other factors (e.g. childhood pneumococcal vaccination) would expand understanding of these findings. Keywords: infectious diseases; water; water access (Published: 5 August 2013) This paper is part of Supplement 1, 2013, ICCH15 Proceedings . More papers from this Supplement can be found here . Citation: Int J Circumpolar Health 2013, 72 : 21233 - http://dx.doi.org/10.3402/ijch.v72i0.21233

Terminating a conflict under favorable conditions has been one of the most difficult tasks facing our nation's political and military leaders. Too frequently, history has shown that our fighting forces have been committed to conflicts in which there is no clear vision of the desired end-state or without military objectives that will help achieve national aims. This paper examines the role of military strategy in conflict termination. While U.S. military doctrine now links the strategic political aims of war and the battlefield tactical engagement, the military will continue to face a difficult task in formulating conflict termination strategies due to the lack of specificity in our national security strategy. Given this conclusion and the increasing complexity and frequency of conflicts in the post-Cold war environment, additional conflict termination guidance is required in U.S. military doctrine. Conflict termination, Military strategy.

Background: There is need for locally-derived age-specific clinical laboratory reference ranges of healthy Africans in subSaharan Africa. Reference values from North American and European populations are being used for African subjects despite previous studies showing significant differences. Our aim was to establish clinical laboratory reference values for African adolescents and young adults that can be used in clinical trials and for patient management. Methods and Findings: A panel of 298, HIV-seronegative individuals aged 13–34 years was randomly selected from participants in two population-based cross-sectional surveys assessing HIV prevalence and other sexually transmitted infections in western Kenya. The adolescent (,18 years)-to-adults ($18 years) ratio and the male-to-female ratio was 1:1. Median and 95% reference ranges were calculated for immunohematological and biochemistry values. Compared with U.Sderived reference ranges, we detected lower hemoglobin (HB), hematocrit (HCT), red blood cells (RBC), mean corpuscular volume (MCV), neutrophil, glucose, and blood urea nitrogen values but elevated eosinophil and total bilirubin values. Significant gender variation was observed in hematological parameters in addition to T-bilirubin and creatinine indices in all age groups, AST in the younger and neutrophil, platelet and CD4 indices among the older age group. Age variation was also observed, mainly in hematological parameters among males. Applying U.S. NIH Division of AIDS (DAIDS) toxicity grading to our results, 40% of otherwise healthy study participants were classified as having an abnormal laboratory parameter (grade 1–4) which would exclude them from participating in clinical trials. Conclusion: Hematological and biochemistry reference values from African population differ from those derived from a North American population, showing the need to develop region-specific reference values. Our data also show variations in hematological indices between adolescent and adult males which should be considered when developing reference ranges. This study provides the first locally-derived clinical laboratory reference ranges for adolescents and young adults in western Kenya.

Timothy Thomas and colleagues report the results of the Kisumu breastfeeding study (Kenya), a single-arm trial that assessed the feasibility and safety of a triple-antiretroviral regimen to suppress maternal HIV load in late pregnancy., Background Effective strategies are needed for the prevention of mother-to-child HIV transmission (PMTCT) in resource-limited settings. The Kisumu Breastfeeding Study was a single-arm open label trial conducted between July 2003 and February 2009. The overall aim was to investigate whether a maternal triple-antiretroviral regimen that was designed to maximally suppress viral load in late pregnancy and the first 6 mo of lactation was a safe, well-tolerated, and effective PMTCT intervention. Methods and Findings HIV-infected pregnant women took zidovudine, lamivudine, and either nevirapine or nelfinavir from 34–36 weeks' gestation to 6 mo post partum. Infants received single-dose nevirapine at birth. Women were advised to breastfeed exclusively and wean rapidly just before 6 mo. Using Kaplan-Meier methods we estimated HIV-transmission and death rates from delivery to 24 mo. We compared HIV-transmission rates among subgroups defined by maternal risk factors, including baseline CD4 cell count and viral load. Among 487 live-born, singleton, or first-born infants, cumulative HIV-transmission rates at birth, 6 weeks, and 6, 12, and 24 mo were 2.5%, 4.2%, 5.0%, 5.7%, and 7.0%, respectively. The 24-mo HIV-transmission rates stratified by baseline maternal CD4 cell count, Editors' Summary Background Every year, about half a million children become infected with human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS). Nearly all these newly infected children live in resource-limited countries and most acquire HIV from their mother, so-called mother-to-child transmission (MTCT). Without intervention, 25%–50% of babies born to HIV-positive mothers become infected with HIV during pregnancy, delivery, or breastfeeding. This infection rate can be reduced by treating mother and child with antiretroviral (ARV) drugs. A single dose of nevirapine (a “non-nucleoside reverse transcriptase inhibitor” or NNRTI) given to the mother at the start of labor and to her baby soon after birth nearly halves the risk of MTCT. Further reductions in risk can be achieved by giving mother and baby three ARVs—an NNRTI and two nucleoside reverse transcriptase inhibitors (NRTIs such as zidovudine and lamivudine)—during pregnancy and perinatally (around the time of birth). Why Was This Study Done? Breastfeeding is crucial for child survival in poor countries but it is also responsible for up to half of MTCT. Consequently, many researchers are investigating how various ARV regimens given to mothers and/or their infants during the first few months of life as well as during pregnancy and perinatally affect MTCT. In this single-arm trial, the researchers assess the feasibility and safety of using a triple-ARV regimen to suppress the maternal HIV load (amount of virus in the blood) from late pregnancy though 6 months of breastfeeding among HIV-positive women in Kisumu, Kenya, and ask whether this approach achieves a lower HIV transmission rate than other ARV regimens that have been tested in resource-limited settings. In a single-arm trial, all the participants are given the same treatment. By contrast, in a “randomized controlled” trial, half the participants chosen at random are given the treatment under investigation and the rest are given a control treatment. A randomized controlled trial provides a better comparison of treatments than a single-arm trial but is more costly. What Did the Researchers Do and Find? In the Kisumu Breastfeeding Study (KiBS), HIV-infected pregnant women took a triple-ARV regimen containing zidovudine and lamivudine and either nevirapine or the protease inhibitor nelfinavir from 34–36 weeks of pregnancy to 6 months after delivery. They were advised to breastfeed their babies (who received single-dose nevirapine at birth), and to wean them rapidly just before 6 months. The researchers then used Kaplan-Meier statistical methods to estimate HIV transmission and death rates among 487 live-born infants from delivery to 24 months. The cumulative HIV transmission rate rose from 2.5% at birth to 7.0% at 24 months. The cumulative HIV transmission or death rate at 24 months was 15.7%; no infant deaths were attributed to ARVs. At 24 months, 3.0% of babies born to mothers with a low viral load were HIV positive compared to 8.7% of babies born to mothers with a high viral load, a statistically significant difference. Similarly, at 24 months, 8.4% of babies born to mothers with low baseline CD4 cell counts (CD4 cells are immune system cells that are killed by HIV; CD4 cell counts indicate the level of HIV-inflicted immune system damage) were HIV positive compared to 4.1% of babies born to mothers with high baseline CD4 cell counts, although this difference did not achieve statistical significance. What Do These Findings Mean? Although these findings are limited by the single-arm design, they support the idea that giving breastfeeding women a triple-ARV regimen from late pregnancy to 6 months is a safe, feasible way to reduce MTCT in resource-limited settings. The HIV transmission rates in this study are comparable to those recorded in similar trials in other resource-limited settings and are lower than MTCT rates observed previously in Kisumu in a study in which no ARVs were used. Importantly, the KiBS mothers took most of the ARVs they were prescribed and most stopped breastfeeding by 6 months as advised. The intense follow-up employed in KiBS may be partly responsible for this good adherence to the trial protocol and thus this study's findings may not be generalizable to all resource-limited settings. Nevertheless, they suggest that a simple triple-ARV regimen given to HIV-positive pregnant women regardless of their baseline CD4 cell count can reduce MTCT during pregnancy and breastfeeding in resource-limited setting. Additional Information Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001015. The accompanying PLoS Medicine Research article by Zeh and colleagues describes the emergence of resistance to ARVs in KiBS Information on HIV and AIDS is available from the US National Institute of Allergy and Infectious Diseases HIV InSite has comprehensive information on all aspects of HIV/AIDS Information is available from Avert, an international AIDS charity, on many aspects of HIV/AIDS, including information on children, HIV, and AIDS and on preventing mother-to-child transmission of HIV (in English and Spanish) UNICEF also has information about children and HIV and AIDS (in several languages) The World Health organization has information on mother-to-child transmission of HIV http://www.who.int/hiv/topics/mtct/en/index.html (in several languages)

Space based optical communications systems that communicate with several satellites need a method to simultaneously track multiple platforms and receive low rate data from each platform. The tracking and data link are required to manage the communications network and to facilitate rapid switching of a high data rate optical link. We will describe a proof-of-concept (POC) system that utilizes a high speed area array detector to simultaneously track and receive data from multiple optical communications beacons. The tracking has sufficient precision to permit rapid acquisition and tracking of any of the beacons by a high speed optical link. The sensitivity of the system is sufficient to permit open loop pointing of divergent beacons. The beacon can be modulated at kilobit/sec rates and the tracking system is capable of synchronizing and extracting the data from all the beacons being tracked.

A prototype raster multibeam optics is evaluated for 45 nm mask pilot lithography. A laser beam is split into 32 beamlets, which are modulated acousto-optically then focused onto a photocathode. This generates 32 electron beams which are scanned and focused on a writing surface. Photocathode photoyield and lifetime exceed 200 nA/mW and 100 h per spot, respectively. Photoyield recovers to within 1% after 1 min fully extinguished. The size of the laser spot is 300 nm, full width half maximum (FWHM) and the size of the corresponding electron beam spots is 50 nm (FWHM) at the writing plane. In the first demonstration of multiple electron beam lithography, 200 nm line/space arrays and 100 nm isolated lines were printed with an interim four-beam datapath. Preliminary experiments and a theoretical evaluation indicate that resist outgassing does not significantly reduce photocathode performance. An improved electron-optical column has also been designed, with a 35 nm pixel pitch, and a placement accuracy of

An acousto-optic device comprises a first light source for producing a light beam, a light-transmitting material capable of transmitting the light beam along an optical path through the light-transmitting material, a light-absorbing material adjacent to the light-transmitting material, and a pulsed light source capable of directing a pulsed light beam at the light absorbing material so as to produce acoustic waves within the light-transmitting material that cross the optical path of the light beam from the first light source.

A prototype raster multibeam lithography tool was constructed and is being evaluated for use as a mask writer at the 50 nm node. The photocathode illumination module (PIM) focuses a linear brush of 32 individually modulated laser beams into 300 nm full width at half maximum spots on the surface of a photocathode. The PIM has been module tested with satisfactory results and integrated into the prototype tool. A new electron-beam photocathode gun and column have also been integrated into the tool. The tool has generated a linear array of 32 electron beams which have been magnified and focused onto a YAG screen as well as demagnified and scanned across a knife edge. Preliminary results have produced 86 nm spots at the writing plane.

A neural network was trained to learn the associations between speech acoustics, suitably transformed and normalized, and associated articulatory movements, which were recorded at the University of Wisconsin x‐ray microbeam facility. Training was done on the numbers “one” through “ten” spoken by a female speaker; articulatory templates were selected from her speech. Speech from a male speaker was transformed and normalized and passed through the trained neural network. Articulatory movements inferred from his speech by the neural network were compared, by Euclidian distance, with the templates from the speech of the female speaker. To assign a single point of match for each template, an extremum finding algorithm was passed over the function that relates temporal position to degree of match. A threshold, defined as a distance of more than two standard deviations from the mean of the distance measure taken at each step in the speech sample, was used to successfully recognize the words spoken. Enhanced disc...

The potential enhancement of ballistic and mechanical properties from electroslag remelting has fostered an interest in mechanical property characterizations of electroslag remelted (ESR) steels for Army applications. Mechanical property data are presented for quenched and tempered ESR 4353 and ESR 4340 steels. Hardness decreases from 61.1 to 44.4 HRC as tempering temperature increases from 300 to 900° F for ESR 4353 steel. Correspondingly, fracture toughness (KIQ) increases from 23.4 ksi √in. to 89.7 ksi √in. The ESR 4353 steel exhibits Charpy impact energy values of 12.4 ft-1b for 400 and 450° F tempers, which decrease to 9.2 ft-lb for a 500° F temper as a result of tempered martensite embrittlement. The percentage of retained austenite decreases to approximately zero as tempering temperature increases to 500° F. Mechanical properties for similarly heat treated ESR 4340 steel are obtained from literature data. Results indicate that for a given tempering temperature or hardness, the ESR 4340 steel has greater Charpy impact energy and fracture toughness (KIQ).

The operation of an apparatus constructed to measure absolute photodissociation spectra of ions and to determine the kinetic energy spectrum of the photoproducts by time‐of‐flight analysis is described. Photodissociation spectra for the processes D+2+hν→D++D and N2O+→NO++N have been obtained, and the photodissociation cross sections for HD++hν→H++D and HD++hν→D++H have been measured. The photodissociation spectrum of D+2, using an irradiation bandwidth of

The photodissociation spectrum of SO+2 corresponding to the process SO+2 +hν→SO++O has been measured on a triple quadrupole system for the wavelength ranges: 3000–3400 and 4400–5120 A. The spectrum in the visible has been assigned to the C 2B1←A 2A2 transition and vibrational structure analyzed to yield λ00=4187 A, the harmonic vibrational frequencies ν’1=953 cm−1, ν’’2=499 cm−1, ν’1=767 cm−1, and ν2 =410 cm−1, and the anharmonicity constants X‘11 =−6.3 cm−1, X’’12 =−6.1 cm−1, X‘22 =−4.2 cm−1, X12 =−6.3 cm−1, and X’22 =−7.4 cm−1. Apparent photodissociation cross sections ranged from ∼1×10−20–1.6×10−19 cm2 in the visible spectrum. In the UV spectrum the highly congested vibrational structure could not be resolved sufficiently for analysis; photodissociation cross sections ranged from ∼2–4×10−19 cm2 with broad bands roughly corresponding to expected progression in ν1 and ν’2 within the C 2B1←X 2A1 electronic transition. The process SO+2 +hν→S++O2 showed an onset near 3108 A and the corresponding pho...

The U.S. Army Materials Technology Laboratory (MTL) selected electroslag remelted (ESR) 4340 steel as a candidate steel armor on the Mobile Protected Gun System (MPGS). This investigation characterizes the material in terms of mechanical properties and microstructure. Also, a ladle refined, electric furnace (EF) 4340 steel was brought into this characterization for evaluation as a less costly alternative with respect to processing costs to ESR 4340 steel in terms of mechanical properties.