Verification Run Research Articles

High-resolution Dayside Spectroscopy of WASP-189 b: Detection of Iron during the GHOST/Gemini South System Verification Run

With high equilibrium temperatures and tidally locked rotation, ultra-hot Jupiters (UHJs) are unique laboratories within which to probe extreme atmospheric physics and chemistry. In this paper, we present high-resolution dayside spectroscopy of the UHJ WASP-189 b obtained with the new Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South Observatory. The observations, which cover 3 hr of post-eclipse orbital phases, were obtained during the instrument’s System Verification run. We detect the planet’s atmosphere via the Doppler cross-correlation technique, and recover a detection of neutral iron in the planet’s dayside atmosphere at a significance of 7.5σ in the red arm of the data, verifying the presence of a thermal inversion. We also investigate the presence of other species in the atmosphere and discuss the implications of model injection/recovery tests. These results represent the first atmospheric characterization of an exoplanet with GHOST’s high-resolution mode, and demonstrate the potential of this new instrument in detecting and studying ultra-hot exoplanet atmospheres.

Development of a New Progressive Nonintrusive Theory to Reduce Computation Time with Particle-in-Fluid Flow Application

Summary Solid-in-fluid flow studies and modeling approaches are categorized mainly based on the scale at which solid particles are modeled. Eulerian-Eulerian approaches treat solid at the same scale as fluid. These approaches are fast but suffer from improper physics and high dispersion effect due to averaging solid properties to upscale them to the fluid scale. Eulerian-Lagrangian methods try to solve the issue by modeling each particle individually. Modeling movement of each particle in fluid is complex, especially when modeling individual particle interaction with other particles and fluid is involved. Although such an approach is favorable due to its high accuracy in modeling solid behavior, it is computationally intensive and very time-consuming. It may take hours or even days to simulate a few seconds of a solid-in-fluid flow process when number of particles grows and goes beyond one thousand. In this paper, a theory is developed to reproduce and predict solid state variables such as location and velocity with a reasonable accuracy but at least four orders of magnitude faster. This solution uses the available information from previously finished simulations to build a progressive nonintrusive formulation based on the trajectory piecewise linearization (TPWL) theory that reproduces and predicts particles locations and velocities. Reproduction or prediction run accuracy is verified by comparing the results against a verification run and the reduction in computation time is also measured. The progressive nonintrusive formulation developed in this work is universal and is not limited to solid-in-fluid flow applications such as particle transport in wellbore or hydraulic fracture in petroleum engineering, and it can be applied to other engineering or science problems too.

Universal Qualification of Near Ultraviolet Circular Dichroism Spectroscopy: Method Performance Parameters and Limits of Detection for Structural Differences

Analytical methods must be qualified as part of the method development lifecycle for product characterization of biotherapeutics. For higher order structure characterization methods, such as near ultraviolet circular dichroism spectroscopy, qualification is performed to determine the expected variability of the method and to establish criteria for analytical product comparability, reference standard qualification, and analytical similarity evaluations. Typical method qualifications require a single product to be tested across several days with multiple replicates, essential to establish a quantitative limit for future product evaluation studies, which may be burdensome with respect to time, instrumentation, and material requirements. In this note, a methodology is proposed to expedite the qualification process for the near ultraviolet circular dichroism spectroscopy method, decreasing the number of required qualification runs, in many cases, to just one for each product. The significant reduction in the number of assays for qualification is achieved by utilizing historical data that applies universally across products of variable classification, size, and test date. Despite their differences, the products exhibit comparable method performance when compared to a product-specific reference standard, and a universal detection threshold is established for application to future product evaluations that meet pre-determined method suitability criteria following a single verification run.

The NIKA2 large-field-of-view millimetre continuum camera for the 30 m IRAM telescope

Context. Millimetre-wave continuum astronomy is today an indispensable tool for both general astrophysics studies (e.g. star formation, nearby galaxies) and cosmology (e.g. cosmic microwave background and high-redshift galaxies). General purpose, large-field-of-view instruments are needed to map the sky at intermediate angular scales not accessible by the high-resolution interferometers (e.g. ALMA in Chile, NOEMA in the French Alps) and by the coarse angular resolution space-borne or ground-based surveys (e.g. Planck, ACT, SPT). These instruments have to be installed at the focal plane of the largest single-dish telescopes, which are placed at high altitude on selected dry observing sites. In this context, we have constructed and deployed a three-thousand-pixel dual-band (150 GHz and 260 GHz, respectively 2 mm and 1.15 mm wavelengths) camera to image an instantaneous circular field-of-view of 6.5 arcmin in diameter, and configurable to map the linear polarisation at 260 GHz. Aims. First, we are providing a detailed description of this instrument, named NIKA2 (New IRAM KID Arrays 2), in particular focussing on the cryogenics, optics, focal plane arrays based on Kinetic Inductance Detectors, and the readout electronics. The focal planes and part of the optics are cooled down to the nominal 150 mK operating temperature by means of an adhoc dilution refrigerator. Secondly, we are presenting the performance measured on the sky during the commissioning runs that took place between October 2015 and April 2017 at the 30-m IRAM telescope at Pico Veleta, near Granada (Spain). Methods. We have targeted a number of astronomical sources. Starting from beam-maps on primary and secondary calibrators we have then gone to extended sources and faint objects. Both internal (electronic) and on-the-sky calibrations are applied. The general methods are described in the present paper. Results. NIKA2 has been successfully deployed and commissioned, performing in-line with expectations. In particular, NIKA2 exhibits full width at half maximum angular resolutions of around 11 and 17.5 arcsec at respectively 260 and 150 GHz. The noise equivalent flux densities are, at these two respective frequencies, 33±2 and 8±1 mJy s1/2. A first successful science verification run was achieved in April 2017. The instrument is currently offered to the astronomy community and will remain available for at least the following ten years.

The Dark Energy Survey: Status and First results

The observational results of the latest 15 to 20 years have stablished a standard model for the cosmology which has some amazing consequences. A mysterious entity, the dark energy, has been confirmed as the dominant component of the Universe, and is also responsible for its accelerated expansion. However, its physical nature remains unknown. Unveiling the nature of the dark energy is one of the main problems of cosmology. A powerful way of studying this problem is the measurement of different and complementary probes of the dark energy in very large galaxy surveys. The Dark Energy Survey (DES) is an optical and near infrared survey that is imaging 5000 deg2 of the southern celestial hemisphere in five broad bandpass filters, to study the properties of this mysterious dark energy. In order to perform such a survey, a new CCD camera of 3 deg2 field of view has been mounted on the Blanco 4m telescope at Cerro Tololo (Chile). The survey observations started in 2012, with the science verification run. DES will study the dark energy properties using four independent methods: galaxy clusters counts and distributions, weak gravitational lensing tomography, baryon acoustic oscillations and supernovae Ia distances. Obtaining the four measurements from the same data set will allow a strict control of the systematic uncertainties to obtain a robust and precise determination of the cosmological parameters. Here, the first scientific results of the project, based on science verification data and related to photometric redshifts and galaxy shape measurements, are presented.

High precision radial velocities with GIANO spectra

Radial velocities (RV) measured from near-infrared (NIR) spectra are a potentially excellent tool to search for extrasolar planets around cool or active stars. High resolution infrared (IR) spectrographs now available are reaching the high precision of visible instruments, with a constant improvement over time. GIANO is an infrared echelle spectrograph at the Telescopio Nazionale Galileo (TNG) and it is a powerful tool to provide high resolution spectra for accurate RV measurements of exoplanets and for chemical and dynamical studies of stellar or extragalactic objects. No other high spectral resolution IR instrument has GIANO's capability to cover the entire NIR wavelength range (0.95-2.45 micron) in a single exposure. In this paper we describe the ensemble of procedures that we have developed to measure high precision RVs on GIANO spectra acquired during the Science Verification (SV) run, using the telluric lines as wavelength reference. We used the Cross Correlation Function (CCF) method to determine the velocity for both the star and the telluric lines. For this purpose, we constructed two suitable digital masks that include about 2000 stellar lines, and a similar number of telluric lines. The method is applied to various targets with different spectral type, from K2V to M8 stars. We reached different precisions mainly depending on the H -magnitudes: for H ~ 5 we obtain an rms scatter of ~ 10 m s-1, while for H ~ 9 the standard deviation increases to ~ 50 - 80 m s-1. The corresponding theoretical error expectations are ~4 m s-1 and 30 m s-1, respectively. Finally we provide the RVs measured with our procedure for the targets observed during GIANO Science Verification.

Coverage Estimation in Model Checking with Bitstate Hashing

Explicit-state model checking which is conducted by state space search has difficulty in exploring satisfactory state space because of its memory requirements. Though bitstate hashing achieves memory efficiency, it cannot guarantee complete verification. Thus, it is desirable to provide a reliability indicator such as a coverage estimate. However, the existing approaches for coverage estimation are not very accurate when a verification run covers a small portion of state space. This mainly stems from the lack of information that reflects characteristics of models. Therefore, we propose coverage estimation methods using a growth curve that approximates an increase in reached states by enlarging a bloom filter. Our approaches improve estimation accuracy by leveraging the statistics from multiple verification runs. Coverage is estimated by fitting the growth curve to these statistics. Experimental results confirm the validity of the proposed growth curve and the applicability of our approaches to practical models. In fact, for practical models, our approaches outperformed the conventional ones when the actual coverage is relatively low.

Verifying systems rules using rule-directed symbolic execution

Systems code must obey many rules, such as "opened files must be closed." One approach to verifying rules is static analysis, but this technique cannot infer precise runtime effects of code, often emitting many false positives. An alternative is symbolic execution, a technique that verifies program paths over all inputs up to a bounded size. However, when applied to verify rules, existing symbolic execution systems often blindly explore many redundant program paths while missing relevant ones that may contain bugs. Our key insight is that only a small portion of paths are relevant to rules, and the rest (majority) of paths are irrelevant and do not need to be verified. Based on this insight, we create WOODPECKER, a new symbolic execution system for effectively checking rules on systems programs. It provides a set of builtin checkers for common rules, and an interface for users to easily check new rules. It directs symbolic execution toward the program paths relevant to a checked rule, and soundly prunes redundant paths, exponentially speeding up symbolic execution. It is designed to be heuristic-agnostic, enabling users to leverage existing powerful search heuristics. Evaluation on 136 systems programs totaling 545K lines of code, including some of the most widely used programs, shows that, with a time limit of typically just one hour for each verification run, WOODPECKER effectively verifies 28.7% of the program and rule combinations over bounded input, whereas an existing symbolic execution system KLEE verifies only 8.5%. For the remaining combinations, WOODPECKER verifies 4.6 times as many relevant paths as KLEE. With a longer time limit, WOODPECKER verifies much more paths than KLEE, e.g., 17 times as many with a fourhour limit. WOODPECKER detects 113 rule violations, including 10 serious data loss errors with 2 most serious ones already confirmed by the corresponding developers.

Verifying systems rules using rule-directed symbolic execution

Systems code must obey many rules, such as "opened files must be closed." One approach to verifying rules is static analysis, but this technique cannot infer precise runtime effects of code, often emitting many false positives. An alternative is symbolic execution, a technique that verifies program paths over all inputs up to a bounded size. However, when applied to verify rules, existing symbolic execution systems often blindly explore many redundant program paths while missing relevant ones that may contain bugs. Our key insight is that only a small portion of paths are relevant to rules, and the rest (majority) of paths are irrelevant and do not need to be verified. Based on this insight, we create WOODPECKER, a new symbolic execution system for effectively checking rules on systems programs. It provides a set of builtin checkers for common rules, and an interface for users to easily check new rules. It directs symbolic execution toward the program paths relevant to a checked rule, and soundly prunes redundant paths, exponentially speeding up symbolic execution. It is designed to be heuristic-agnostic, enabling users to leverage existing powerful search heuristics. Evaluation on 136 systems programs totaling 545K lines of code, including some of the most widely used programs, shows that, with a time limit of typically just one hour for each verification run, WOODPECKER effectively verifies 28.7% of the program and rule combinations over bounded input, whereas an existing symbolic execution system KLEE verifies only 8.5%. For the remaining combinations, WOODPECKER verifies 4.6 times as many relevant paths as KLEE. With a longer time limit, WOODPECKER verifies much more paths than KLEE, e.g., 17 times as many with a fourhour limit. WOODPECKER detects 113 rule violations, including 10 serious data loss errors with 2 most serious ones already confirmed by the corresponding developers.

VLT/X-shooter Spectroscopy of a dusty planetary nebula discovered withSpitzer/IRS

As part of a mid-infrared spectroscopic survey of young stars with the Spitzer Space Telescope, an unclassified red emission line object was discovered. Based on its high ionization state indicated by the Spitzer spectrum, this object could either be a dusty Supernova Remnant (SNR) or a Planetary Nebula (PN). In this research note, the object is classified and the available spectroscopic data are presented to the community for further analysis. UV/optical/NIR spectra were obtained during the science verification run of the VLT/X-shooter. A large number of emission lines are identified allowing the determination of the nature of this object. The presence of strong, narrow (Delta_v ~ 8 - 74 km/s) emission lines, combined with very low line ratios of, e.g., [N II]/Halpha and [S II]/Halpha show that the object is a Planetary Nebula (PN) that lies at an undetermined distance behind the Serpens Molecular Cloud. This illustrates the potential of X-shooter as an efficient tool for constraining the nature of faint sources with unknown spectral properties or colors.

A lazy approach to symmetry reduction

Abstract Symmetry reduction is a technique to counter state explosion for systems with regular structure. It relies on idealistic assumptions about indistinguishable components, which in practice may only be similar. In this article, we present a flexible, lazy approach to symmetry-reducing a structure without any prior knowledge about its global symmetry. Instead of a-priori checking for compliance with symmetry conditions, each encountered state is annotated on the fly with information about how symmetry is violated along the path leading to it. The method naturally favors “very symmetric” systems: more similarity among the components leads to greater compression. A notion of subsumption is used to prune the annotated search space during exploration. Previous solutions to the approximate symmetry reduction problem are restricted to specific types of asymmetry, such as up to bisimilarity, or incur a large overhead, either during preprocessing of the structure or during the verification run. In contrast, the strength of our method is its balance between ease of implementation and algorithmic flexibility. We include analytic and experimental results that witness its efficiency.

The Design of a Multicore Extension of the SPIN Model Checker

We describe an extension of the SPIN model checker for use on multicore shared-memory systems and report on its performance. We show how, with proper load balancing, the time requirements of a verification run can, in some cases, be reduced close to N-fold when N processing cores are used. We also analyze the types of verification problems for which multicore algorithms cannot provide relief. The extensions discussed here require only relatively small changes in the SPIN source code and are compatible with most existing verification modes such as partial order reduction, the verification of temporal logic formulas, bitstate hashing, and hash-compact compression.

A First Study of Giant Stars in the Galactic Bulge based on Crires spectra

We present our on-going work on the determination of elemental abundances of giants in the Galactic Bulge by means of infrared spectroscopy. We show a preliminarily reduced spectrum and a synthetic spectrum fit of the Bulge giant Arp 4203 recorded with the near-infrared, high-resolution Crires spectrograph mounted on the VLT during its science verification run in August 2006. Abundances derived from this spectrum are discussed.

Reduced-order optimal control of water flooding using proper orthogonal decomposition

Model-based optimal control of water flooding generally involves multiple reservoir simulations, which makes it into a time-consuming process. Furthermore, if the optimization is combined with inversion, i.e., with updating of the reservoir model using production data, some form of regularization is required to cope with the ill-posedness of the inversion problem. A potential way to address these issues is through the use of proper orthogonal decomposition (POD), also known as principal component analysis, Karhunen–Loeve decomposition or the method of empirical orthogonal functions. POD is a model reduction technique to generate low-order models using ‘snapshots’ from a forward simulation with the original high-order model. In this work, we addressed the scope to speed up optimization of water-flooding a heterogeneous reservoir with multiple injectors and producers. We used an adjoint-based optimal control methodology that requires multiple passes of forward simulation of the reservoir model and backward simulation of an adjoint system of equations. We developed a nested approach in which POD was first used to reduce the state space dimensions of both the forward model and the adjoint system. After obtaining an optimized injection and production strategy using the reduced-order system, we verified the results using the original, high-order model. If necessary, we repeated the optimization cycle using new reduced-order systems based on snapshots from the verification run. We tested the methodology on a reservoir model with 4050 states (2025 pressures, 2025 saturations) and an adjoint model of 4050 states (Lagrange multipliers). We obtained reduced-order models with 20–100 states only, which produced almost identical optimized flooding strategies as compared to those obtained using the high-order models. The maximum achieved reduction in computing time was 35%.

Failure Trace Analysis of Timed Circuits for Automatic Timing Constraints Derivation

This work proposes a technique to automatically obtain timing constraints for a given timed circuit to operate correctly. A designated set of delay parameters of a circuit are first set to sufficiently large bounds, and verification runs followed by failure analysis are repeated. Each verification run performs timed state space enumeration under the given delay bounds, and produces a failure trace if it exists. The failure trace is analyzed, and sufficient timing constraints to prevent the failure are obtained. Then, the delay bounds are tightened according to the timing constraints by using an ILP (Integer Linear Programming) solver. This process terminates when either some delay bounds under which no failure is detected are found or no new delay bounds to prevent the failures can be obtained. The experimental results using a naive implementation show that the proposed method can efficiently handle asynchronous benchmark circuits and nontrivial GasP circuits.

Gemini Multi-Object Spectrograph Integral Field Unit Spectroscopy of the 167-317 (LV2) Proplyd in Orion

We present high spatial resolution spectroscopic observations of the proplyd 167-317 (LV2) near the Trapezium cluster in the Orion Nebula, obtained during the system verification run of the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) at the Gemini South Observatory. We have detected 38 forbidden and permitted emission lines associated with the proplyd and its redshifted jet. We have been able to detect three velocity components in the profiles of some of these lines: a peak with a 28–33 km s-1 systemic velocity that is associated with the photoevaporated proplyd flow, a highly redshifted component associated with a previously reported jet (which has receding velocities of about 80–120 km s-1 with respect to the systemic velocity and which is spatially distributed to the southeast of the proplyd), and a less obvious, approaching structure that may possibly be associated with a faint counterjet with a systemic velocity of -75 ± 15 km s-1. We find evidence that the redshifted jet has a variable velocity, with slow fluctuations as a function of the distance from the proplyd. We present several background-subtracted, spatially distributed emission-line maps, and we use this information to obtain the dynamical characteristics over the observed field. Using a simple model and extinction-corrected Hα fluxes, we estimate the mass-loss rate for both the proplyd photoevaporated flow and the redshifted microjet, obtaining proplyd = (6.2 ± 0.6) × 10-7 M⊙ yr-1 and jet = (2.0 ± 0.7) × 10-8 M⊙ yr-1, respectively.

Science verification results from PMAS

AbstractPMAS, the Potsdam Multi‐Aperture Spectrophotometer, is a new integral field instrument which was commissioned at the Calar Alto 3.5 m Telescope in May 2001. We report on results obtained from a science verification run in October 2001. We present observations of the low‐metallicity blue compact dwarf galaxy SBS0335‐052, the ultra‐luminous X‐ray Source X‐1 in the Holmberg II galaxy, the quadruple gravitational lens system Q2237+0305 (the “Einstein Cross”), the Galactic planetary nebula NGC7027, and extragalactic planetary nebulae in M31. PMAS is now available as a common user instrument at Calar Alto Observatory. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Polynomial Formal Verification of Multipliers

Not long ago, completely automatical formal verification of multipliers was not feasible, even for small input word sizes. However, with Multiplicative Binary Moment Diagrams (aBMD), which is a new data structure for representing arithmetic functions over Boolean variables, methods were proposed by which verification of multipliers with input word sizes of up to 256 Bits is now feasible. Unfortunately, only experimental data has been provided for these verification methods until now. In this paper, we give a formal proof that logic verification with aBMDs is polynomially bounded in both, space and time, when applied to the class of Wallace-tree like multipliers. Using this knowledge online detection of design errors becomes feasible during a verification run.

Optimising the Lithographic Patterning Effect in an Acid Copper Electroplating Process

The effects of the average cathodic current density, electrode separation, and the active area density on the workpiece-level plating thickness variability were studied by factorial experiments for an acid copper pattern electroplating process. All the three parameters and the current density×electrode separation interaction were found to be significant, and an 8-term first-order prediction model was constructed and verified experimentally. The minimum variability achievable was found to increase with the active area density contrast over the board surface, and was explained by the scattering effect of the density contrast on the average plating thickness. A subsequent verification run using a simple circuit pattern showed that a composite parameter involving the overall active area density, the continuum area and the number of density contrasts, was appropriate. The possibility of further reducing the workpiece level variability by investigating the interaction effect between the overall active area density and the density contrast of the substrate was suggested.

Optimization of Concentration of Medium Ingredients for Production of Citric Acid using Statistical Methods

The concentration of medium ingredients was optimized by applying statistical methods for production of citric acid by locally isolated Aspergillus niger PCSIR-06. Box-bhenken design and response surface methodology were applied for designing experiment and statistical analysis of results. The Box-bhenken design limited the number of experiments to fifty four for studying possible interaction between the six medium ingredients i.e., Sucrose, KH2PO4, NH4NO3, MgSO4, zinc and iron. The statistical method predicted maximum citric acid yield of 108.69 g/l with medium ingredients concentration Sucrose 149.92 g/l, KH2PO4 1.25 g/l, NH4NO3, 4.66 g/l, MgSO4 0.15 g/l, Zn 24.00 mg/l, Fe 0.21 mg/l. The verification run confirmed the predicted yield with the given concentration of medium ingredients. These studies successfully demonstrated the use of Box-Bhenken experimental design for the optimization of nutrient concentration for maximum yield of citric acid. Key words: Optimize; Medium; Citric acid; Box-bhenken design; Response surface methodology DOI: http://dx.doi.org/10.3329/bjsir.v46i4.9606 BJSIR 2011; 46(4): 549-560