Applied Research Laboratory at the University of Hawai‘i

We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star–black hole mergers. We infer the binary neutron star merger rate to be between 10 and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>1700</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:msup><a:mrow><a:mi>Gpc</a:mi></a:mrow><a:mrow><a:mo>−</a:mo><a:mn>3</a:mn></a:mrow></a:msup><a:mtext> </a:mtext><a:msup><a:mrow><a:mi>yr</a:mi></a:mrow><a:mrow><a:mo>−</a:mo><a:mn>1</a:mn></a:mrow></a:msup></a:mrow></a:math> and the neutron star–black hole merger rate to be between 7.8 and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>140</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>Gpc</c:mi></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>3</c:mn></c:mrow></c:msup><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>yr</c:mi></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>1</c:mn></c:mrow></c:msup></c:mrow></c:math>, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods used in this work. We infer the binary black hole merger rate, allowing for evolution with redshift, to be between 17.9 and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mn>44</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:msup><e:mrow><e:mi>Gpc</e:mi></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>3</e:mn></e:mrow></e:msup><e:mtext> </e:mtext><e:msup><e:mrow><e:mi>yr</e:mi></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>1</e:mn></e:mrow></e:msup></e:mrow></e:math> at a fiducial redshift (<g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>z</g:mi><g:mo>=</g:mo><g:mn>0.2</g:mn></g:math>). The rate of binary black hole mergers is observed to increase with redshift at a rate proportional to <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mo stretchy="false">(</i:mo><i:mn>1</i:mn><i:mo>+</i:mo><i:mi>z</i:mi><i:msup><i:mo stretchy="false">)</i:mo><i:mi>κ</i:mi></i:msup></i:math> with <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>κ</m:mi><m:mo>=</m:mo><m:mn>2.</m:mn><m:msubsup><m:mn>9</m:mn><m:mrow><m:mo>−</m:mo><m:mn>1.8</m:mn></m:mrow><m:mrow><m:mo>+</m:mo><m:mn>1.7</m:mn></m:mrow></m:msubsup></m:math> for <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>z</o:mi><o:mo>≲</o:mo><o:mn>1</o:mn></o:math>. Using both binary neutron star and neutron star–black hole binaries, we obtain a broad, relatively flat neutron star mass distribution extending from <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:msubsup><q:mn>1.2</q:mn><q:mrow><q:mo>−</q:mo><q:mn>0.2</q:mn></q:mrow><q:mrow><q:mo>+</q:mo><q:mn>0.1</q:mn></q:mrow></q:msubsup></q:math> to <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:msubsup><s:mn>2.0</s:mn><s:mrow><s:mo>−</s:mo><s:mn>0.3</s:mn></s:mrow><s:mrow><s:mo>+</s:mo><s:mn>0.3</s:mn></s:mrow></s:msubsup><s:msub><s:mi>M</s:mi><s:mo stretchy="false">⊙</s:mo></s:msub></s:math>. We confidently determine that the merger rate as a function of mass sharply declines after the expected maximum neutron star mass, but cannot yet confirm or rule out the existence of a lower mass gap between neutron stars and black holes. We also find the binary black hole mass distribution has localized over- and underdensities relative to a power-law distribution, with peaks emerging at chirp masses of <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:msubsup><v:mn>8.3</v:mn><v:mrow><v:mo>−</v:mo><v:mn>0.5</v:mn></v:mrow><v:mrow><v:mo>+</v:mo><v:mn>0.3</v:mn></v:mrow></v:msubsup></v:math> and <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:msubsup><x:mn>27.9</x:mn><x:mrow><x:mo>−</x:mo><x:mn>1.8</x:mn></x:mrow><x:mrow><x:mo>+</x:mo><x:mn>1.9</x:mn></x:mrow></x:msubsup><x:msub><x:mi>M</x:mi><x:mo stretchy="false">⊙</x:mo></x:msub></x:math>. While we continue to find that the mass distribution of a binary’s more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above approximately <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:mn>60</ab:mn><ab:msub><ab:mi>M</ab:mi><ab:mo stretchy="false">⊙</ab:mo></ab:msub></ab:math>, which would indicate the presence of a upper mass gap. Observed black hole spins are small, with half of spin magnitudes below <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:msub><db:mi>χ</db:mi><db:mi>i</db:mi></db:msub><db:mo>≈</db:mo><db:mn>0.25</db:mn></db:math>. While the majority of spins are preferentially aligned with the orbital angular momentum, we infer evidence of antialigned spins among the binary population. We observe an increase in spin magnitude for systems with more unequal-mass ratio. We also observe evidence of misalignment of spins relative to the orbital angular momentum. Published by the American Physical Society 2023

1 Address all correspondences to this author. Phone/fax: (814) 865-5930/863-4128. The use of kriging models for approximation and global optimization has been steadily on the rise in the past decade. The standard approach used in the Design and Analysis of Computer Experiments (DACE) is to use an Ordinary kriging model to approximate a deterministic computer model. Universal and Detrended kriging are two alternative types of kriging models. In this paper, a description on the basics of kriging is given, highlighting the similarities and differences between these three different types of kriging models and the underlying assumptions behind each. A comparative study on the use of three different types of kriging models is then presented using six test problems. The methods of Maximum Likelihood Estimation (MLE) and Cross-Validation (CV) for model parameter estimation are compared for the three kriging model types. A one-dimension problem is first used to visualize the differences between the different models. In order to show applications in higher dimensions, four two-dimension and a 5-dimension problem are also given.

In some communication problems, it is a good assumption that the channel consists of an additive white Gaussian noise forward link and an essentially noiseless feedback link. In this paper, we study channels where no bandwidth constraint is placed on the transmitted signals. Such channels arise in space communications. It is known that the availability of the feedback link cannot increase the channel capacity of the noisy forward link, but it can considerably reduce the coding effort required to achieve a given level of performance. We present a coding scheme that exploits the feedback to achieve considerable reductions in coding and decoding complexity and delay over what would be needed for comparable performance with the best known (simplex) codes for the one-way channel. Our scheme, which was motivated by the Robbins-Monro stochastic approximation technique, can also be used over channels where the additive noise is not Gaussian but is still independent from instant to instant. An extension of the scheme for channels with limited signal bandwidth is presented in a companion paper (Part II).

Packet classification is an enabling function for a variety of Internet applications including quality of service, security, monitoring, and multimedia communications. In order to classify a packet as belonging to a particular flow or set of flows, network nodes must perform a search over a set of filters using multiple fields of the packet as the search key. In general, there have been two major threads of research addressing packet classification, algorithmic and architectural. A few pioneering groups of researchers posed the problem, provided complexity bounds, and offered a collection of algorithmic solutions. Subsequently, the design space has been vigorously explored by many offering new algorithms and improvements on existing algorithms. Given the inability of early algorithms to meet performance constraints imposed by high speed links, researchers in industry and academia devised architectural solutions to the problem. This thread of research produced the most widely-used packet classification device technology, Ternary Content Addressable Memory (TCAM). New architectural research combines intelligent algorithms and novel architectures to eliminate many of the unfavorable characteristics of current TCAMs. We observe that the community appears to be converging on a combined algorithmic and architectural approach to the problem. Using a taxonomy based on the high-level approach to the problem and a minimal set of running examples, we provide a survey of the seminal and recent solutions to the problem. It is our hope to foster a deeper understanding of the various packet classification techniques while providing a useful framework for discerning relationships and distinctions.

We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO's and Advanced Virgo's third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density GW 5.8 10 -9 at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform in the log of the strength of the GWB, with 99% of the sensitivity coming from the band 20-76.6 Hz; GW f 3.4 10 -9 at 25 Hz for a power-law GWB with a spectral index of 2=3 (consistent with expectations for compact binary coalescences), in the band 20-90.6 Hz; and GW f 3.9 10 -10 at 25 Hz for a spectral index of 3, in the band 20-291.6 Hz. These upper limits improve over our previous results by a factor of 6.0 for a flat GWB, 8.8 for a spectral index of 2=3, and 13.1 for a spectral index of 3. We also search for a GWB arising from scalar and vector modes, which are predicted by alternative theories of gravity; we do not find evidence of these, and place upper limits on the strength of GWBs with these polarizations. We demonstrate that there is no evidence of correlated noise of magnetic origin by performing a Bayesian analysis that allows for the presence of both a GWB and an effective magnetic background arising from geophysical Schumann resonances. We compare our upper limits to a fiducial model for the GWB from the merger of compact binaries, updating the model to use the most recent datadriven population inference from the systems detected during O3a. Finally, we combine our results with observations of individual mergers and show that, at design sensitivity, this joint approach may yield stronger constraints on the merger rate of binary black holes at z 2 than can be achieved with individually resolved mergers alone.

Packet classification is an enabling technology for next generation network services and often a performance bottleneck in high-performance routers. The performance and capacity of many classification algorithms and devices, including TCAMs, depend upon properties of filter sets and query patterns. Despite the pressing need, no standard performance evaluation tools or filter sets are publicly available. In response to this problem, we present <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ClassBench</i> , a suite of tools for benchmarking packet classification algorithms and devices. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ClassBench</i> includes a <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">filter set generator </i> that produces synthetic filter sets that accurately model the characteristics of real filter sets. Along with varying the size of the filter sets, we provide high-level control over the composition of the filters in the resulting filter set. The tool suite also includes a <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">trace generator</i> that produces a sequence of packet headers to exercise packet classification algorithms with respect to a given filter set. Along with specifying the relative size of the trace, we provide a simple mechanism for controlling locality of reference. While we have already found <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ClassBench</i> to be very useful in our own research, we seek to eliminate the significant access barriers to realistic test vectors for researchers and initiate a broader discussion to guide the refinement of the tools and codification of a formal benchmarking methodology. (The <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ClassBench</i> tools are publicly available at the following site: http://www.arl.wustl.edu/~det3/ClassBench/.)

An inductively coupled plasma sustained in flowing argon and a permanently aligned all-glass coaxial pneumatic nebulizer are employed in the atomic emission mode with a direct-reading poly-chromator for simultaneous multielement determinations. The inductively coupled plasma is shown to be remarkably free from matrix and interelement effects by application for the determination of major (Na, K, P, Ca, and Mg) and trace (Fe, Cu, Zn, Mn, Pb, Cd, Co, Cr, Ni, V, Ti, Al, Sr, and Ba) elements in reference biologic materials and soil extracts. Wet-digestion and several dry-ashing sample preparation procedures are evaluated. Accuracy, precision, and sensitivity compare favorably with other multielement instrumental techniques (neutron activation analysis, energy dispersive x-ray fluorescence, solution-rotating disk atomic emission spectrometry) and with flame atomic absorption spectrometry. The directness of the method reported here is illustrated by use of one set of system operating conditions with one set of synthetic reference solutions used to establish a single calibration curve for each element.

This tutorial presents the application of wavelet transforms to wideband correlation processing. One major difference between most applications of wavelets and the work presented is the choice of mother wavelet. It focuses on nonorthogonal, continuous mother wavelets, whereas most applications use the orthogonal mother wavelets that were advanced by Daubechies (1988). The continuous wavelet transform then provides an additional tool for studying and gaining insight into wideband correlation processing. In order to understand when wideband processing may be required, its counterpart, narrowband processing, is presented and its limitations are discussed. Identifying those applications requiring wideband processing and presenting techniques to implement the processing are two of the goals of this tutorial article. The underlying tool is the wavelet transform.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper describes the development of an instrument which is analogous to an electron microprobe x-ray analyzer, whereby the electron microprobe is replaced by an ion microprobe, and the x-ray spectrometer by a mass spectrometer. A duoplasmatron is the primary ion source. The primary ion beam is mass separated to eliminate impurity ions. A probe diameter of less than 2 μ at 2×10−10 A is realized for 12-kV Ar+ ions. A new mass spectrometer was developed with the emphasis on high transmission, yet simple construction. It is stigmatic imaging, double focusing, has a mass-resolving power of 300 with a solid acceptance angle of 1.5×10−2 sr (4° half-angle) and a transmitted-energy bandwidth of 10%. It consists of an axially symmetrical electrostatic Einzel lens, a 45° spherical condenser sector, and a magnetic field with plane but inclined pole faces, which deflects the beam by 90°. No entrance slit is used. Experimental results are presented.

The application of new dielectric materials with μ, ϵ, and low loss to antennas is investigated. A zero-order analysis reveals the advantages and limitations of these materials for patch antennas. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26, 75–78, 2000.

We report epitaxial growth of TiN films having low resistivity on (100) silicon substrates using pulsed laser deposition method. The TiN films were characterized using x-ray diffraction, Rutherford backscattering, four-point-probe ac resistivity, high resolution transmission electron microscopy and scanning electron microscopy techniques and epitaxial relationship was found to be 〈100〉 TiN ∥ 〈100〉 Si. TiN films showed 10%–20% channeling yield. In the plane, four unit cells of TiN match with three unit cells of silicon with less than 4.0% misfit. This domain matching epitaxy provides a new mechanism of epitaxial growth in systems with large lattice misfits. Four-point-probe measurements show characteristic metallic behavior of these films as a function of temperature with a typical resistivity of about 15 μΩ cm at room temperature. Implications of low-resistivity epitaxial TiN in silicon device fabrication are discussed.

CAMs are the most popular practical method for implementing packet classification in high performance routers. Their principal drawbacks are high power consumption and inefficient representation of filters with port ranges. A recent paper [Narlikar, et al., 2003] showed how partitioned TCAMs could be used to implement IP route lookup with dramatically lower power consumption. We extend the ideas in [Narlikar, et al., 2003] to address the more challenging problem of general packet classification. We describe two extensions to the standard TCAM architecture. The first organizes the TCAM as a two level hierarchy in which an index block is used to enable/disable the querying of the main storage blocks. The second incorporates circuits for range comparisons directly within the TCAM memory array. Extended TCAMs can deliver high performance (100 million lookups per second) for large filter sets (100,000 filters), while reducing power consumption by a factor of ten and improving space efficiency by a factor of three.

The quantitative analyses and other applications described in this article indicate a useful future for the ionmicroprobe mass analyzer in many areas of the science of solid materials. It should be possible to analyze all the elements quantitatively, but detection sensitivities will vary depending on the matrix, the element, and the polarity of the sputtered ion being studied. Most elements will have optimum yields in the spectrum of positive sputtered ions, and will be detected in concentrations of parts per million in micrometer-sized sampling areas. Electronegative elements will be detected with similar sensitivities in the spectrum of negative sputtered ions, but inert gases, which are ionized with difficulty and have small electron affinities, will be detected with considerably poorer sensitivities. In general, it will be possible to measure isotope ratios without chemical separation of the constituent elemrents of the sample. The precision of an ion microprobe isotope ratio measurement depends basically on the counting rates involved, and its accuracy can approach its precision if auxiliary standards are used. The isotope ratios of different elements can be compared readily because of the small mass-discrimination effects of the system. Surface layers can be quantitatively analyzed in depth with a resolution of tens of angstroms; hence, it should be possible to study the migration of atoms.

The combination of resonant-tunneling diodes and heterostructure field-effect transistors provides a versatile technology for implementing microwave digital and mixed-signal applications. Here we demonstrate and characterize the first monolithic flash analog-to-digital converter (ADC) in this technology. The first-pass ADC achieved 2.7 effective bits at 2 gigasamples per second (Gsps) for a 220-MHz input signal. The one-bit quantizer achieved a single-tone spurious free dynamic range greater than 40 dB at 2 Gsps for a 220-MHz single-tone input with dithering.

We study the distortions induced by peculiar velocities on the redshift-space correlation function of galaxies of di erent morphological types in the Pisces-Perseus redshift survey. Redshift-space distortions a ect early-and late-type galaxies in di erent ways. In particular, at small separations the dominant e ect comes from virialized cluster cores, where ellipticals are the dominant population. The net result is that a meaningful comparison of the clustering strength of di erent morphological types can be performed only in real space, i.e., after projecting out the redshift distortions on the two-point correlation function n). A power-law t to the projected function on scales smaller than 10 h~1 Mpc m(r p , w p (r p ) gives h~1 Mpc, for the early-type population, and h~1 Mpc, r 0 \ 8.35 ~0.76 `0.75 c \ 2.05 ~0.08 `0.10 r 0 \ 5.55 ~0.45 `0.40 for spirals and irregulars. These values are derived for a sample luminosity limited to c \ 1.73 ~0.08 `0.07 We detect a 25% increase of with luminosity for all types combined, from M Zw [19.5. r 0 M Zw \ [19 to [20. In the framework of a simple stable clustering model for the mean streaming of pairs, we estimate the one-dimensional pairwise velocity dispersion between 0 and 1 h~1 Mpc, to be p 12 (1), 865 ~165 `250 km s~1 for early-type galaxies and km s~1 for late types. This latter value should be a fair esti-345 ~65

Additive manufacturing (AM) of metallic parts provides engineers with unprecedented design freedom. This enables designers to consolidate assemblies, lightweight designs, create intricate internal geometries for enhanced fluid flow or heat transfer performance, and fabricate complex components that previously could not be manufactured. While these design benefits may come “free” in many cases, it necessitates an understanding of the limitations and capabilities of the specific AM process used for production, the system-level design intent, and the postprocessing and inspection/qualification implications. Unfortunately, design for additive manufacturing (DfAM) guidelines for metal AM processes are nascent given the rapid advancements in metal AM technology recently. In this paper, we present a case study to provide insight into the challenges that engineers face when redesigning a multicomponent assembly into a single component fabricated using laser-based powder bed fusion for metal AM. In this case, part consolidation is used to reduce the weight by 60% and height by 53% of a multipart assembly while improving performance and minimizing leak points. Fabrication, postprocessing, and inspection issues are also discussed along with the implications on design. A generalized design approach for consolidating parts is presented to help designers realize the freedoms that metal AM provides, and numerous areas for investigation to improve DfAM are also highlighted and illustrated throughout the case study.

In general, the beam patterns of a multiple-beam antenna system may overlap. The degree of overlap is usefully defined by a cross-correlation type of integral which includes phase factors as well as polar diagrams in the description of the beams. It is shown that when beam overlap exists, conservation of energy implies the unavoidable existence of cross couplings between the feed lines, and a related limitation on the radiation efficiency (or correspending receiving cross section) of any single beam. Quantitative relationships are derived describing these limitations, and examples given. The implied character of the scattering matrix, comprised of the array of cross-coupling factors, is also discussed with especial emphasis on lossless, reciprocal systems.

A promising route for the synthesis of large-area graphene, suitable for standard device fabrication techniques, is the sublimation of silicon from silicon carbide at elevated temperatures (>1200 degrees C). Previous reports suggest that graphene nucleates along the (110n) plane, known as terrace step edges, on the silicon carbide surface. However, to date, a fundamental understanding of the nucleation of graphene on silicon carbide is lacking. We provide the first direct evidence that nucleation of epitaxial graphene on silicon carbide occurs along the (110n) plane and show that the nucleated graphene quality improves as the synthesis temperature is increased. Additionally, we find that graphene on the (110n) plane can be significantly thicker than its (0001) counterpart and appears not to have a thickness limit. Finally, we find that graphene along the (110n) plane can contain a high density of structural defects, often the result of the underlying substrate, which will undoubtedly degrade the electronic properties of the material. Addressing the presence of non-uniform graphene that may contain structural defects at terrace step edges will be key to the development of a large-scale graphene technology derived from silicon carbide.

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

A method of calculating the energies of bound states associated with imperfections described by short-range potentials in semiconductors is presented and applied. The method is based on solid-state scattering theory and involves expansion of physical quantities in terms of the Wannier functions for a many-band system. The properties of Bloch functions and Wannier functions are investigated to enable the numerical computation of matrix elements. Application is made to the neutral vacancy in silicon. A pseudopotential is employed to represent the change in the crystal potential produced by the vacancy. It is found that the vacancy produces a localized state in which low-lying energy bands and interband couplings are important, in contrast to the shallow donor and acceptor states which have been studied in the past.