Automating requirements analysis and test case generation

Requirements Engineering - Writing clear and unambiguous requirements that are conflict-free and complete is no easy task. Incorrect requirements lead to errors being introduced early in the design...     

Synthesis and some properties of PVC-bound dimethylglyoxime complexes of Co(II), Ni(II), and Cu(II)

Poly(vinyl chloride) (PVC) has been reacted with dimethylglyoxime (DMG) in THF to form the PVC–DMG comples, which has been characterized by spectroscopic and elemental analyses. The latter indicate that there is one DMG moiety anchored on the PVC chain by displacing every 12th Cl atom in the chain. PVC–DMG has further been reacted with alcoholic solutions of Co(II), Ni(II), and Cu(II) to form the intensely colored PVC–DMG–M(II) complexes. The structures of these complexes have been analyzed by elemental and IR spectral analyses. The overall thermal stability of PVC–DMG–M(II) increases in the order: PVC < PVC–DMG–Cu(II) < PVC–DMG–Ni(II) < PVC–DMG–Co(II). The electrical conductivities are also significantly enhanced in the same order. The permittivities of these complexes are high relative to PVC at low frequency falling gradually with increasing frequency and the dielectric loss-frequency behavior is very broad.     

Design of Dual Band and Tri-band Bandpass Filter (BPF) with Improved Inter-band Isolation Using DGS Integrated Coupled Microstrip Lines Structures

Wireless Personal Communications - A novel approach to design dual-band as well as a triple-band BPF with improved isolation is ventured in this paper. In dual-band filter, dual mode property of...     

Global software development

The last several decades have witnessed a steady, irreversible trend toward the globalization of business, and of software-intensive high-technology businesses in particular. Economic forces are relentlessly turning national markets into global markets and spawning new forms of competition and cooperation that reach across national boundaries. This change is having a profound impact not only on marketing and distribution but also on the way produces are conceived, designed, constructed, tested, and delivered to customers. The author considers how software development is increasingly a multisite, multicultural, globally distributed undertaking     

Instrumented drop-weight test results for normalised and tempered 9Cr1Mo steel

From instrumented drop-weight tests, the nil ductility transition temperature (T_NDT), and a conservative estimate of dynamic fracture toughness (K_Id), at T_NDT for normalised and tempered 9Cr---1Mo steel, are determined to be −25°C and 70 MPa√m, respectively. The latter value agrees well with that determined from pre-cracked Charpy tests. The K_Id/σ_Yd (σ_Yd is the dynamic yield stress) ratio at T_NDT is estimated to be 0·076 √m, in agreement with previous estimates. The uncertainties in crack profile measurement and effect of microstructural variation in the heat affected zone on fracture loads are also discussed.     

Nucleotide-Driven Molecular Sensing of Monkeypox Virus Through Hierarchical Self-Assembly of 2D Hafnium Disulfide Nanoplatelets and Gold Nanospheres

Liquid interfaces facilitate the organization of nanometer-scale biomaterials with plasmonic properties suitable for molecular diagnostics. Using hierarchical assemblage of 2D hafnium disulfide nanoplatelets and zero-dimensional spherical gold nanoparticles, the design of a multifunctional material is reported. When the target analyte is present, the nanocomposites’ self-assembling pattern changes, altering their plasmonic response. Using monkeypox virus (MPXV) as an example, the findings reveal that adding genomic DNA to the nanocomposite surface increases the agglomeration between gold nanoparticles and decreases the π-stacking distance between hafnium disulfide nanoplatelets. Further, this self-assembled nanomaterial is found to have minimal cross-reactivity toward other pathogens and a limit of detection of 7.6 pg µL⁻¹ (i.e., 3.57 × 10⁴ copies µL⁻¹) toward MPXV. Overall, this study helped to gain a better understanding of the genomic organization of MPXV to chemically design and develop targeted nucleotides. The study has been validated by UV–vis spectroscopy, X-ray diffraction, scanning transmission electron microscopy, surface-enhanced Raman microscopy and electromagnetic simulation studies. To the best knowledge, this is the first study in literature reporting selective molecular detection of MPXV within a few minutes and without the use of any high-end instrumental techniques like polymerase chain reactions.     

Predicting reference temperature from instrumented Charpy V-notch impact tests using modified Schindler procedure for computing dynamic fracture toughness

Reactor pressure vessel (RPV) steels are increasingly being characterised in terms of the reference temperature T ₀ and the associated Master Curve (MC) Procedure, following the ASTM E-1921 standard. Though correlations have been proposed to predict the T ₀ from Charpy transition temperature T _28J or instrumented impact test parameters like T _4kN, none can be taken as a universal correlation. Here we are proposing a new correlation of T ₀ with T _0Sch ^dy, where T _0Sch ^dy is the reference temperature corresponding to a median K _Id=100 MPa√m evaluated by the ASTM E1921 procedure applied to K _Id vs T data, and K _Id has been calculated from instrumented CVN impact test data using modified Schindler relations. This will provide a reliable method for determining T ₀ from instrumented CVN tests alone. T _0Sch ^dy provides a conservative alternative to T ₀ ^dy for application of the ASTM E 1921 MC procedure in dynamic situations. Since the above procedure depends only on instrumented CVN data, it will be less costly to apply (no precracking is necessary) and will also obviate the difficulties associated with determining T ₀ ^dy from precracked CVN testing (because of severe size limitations, associated scatter and signal oscillations from the mechanics of the test, there needs to be precise control over test temperatures and test velocity for obtaining valid data from limited number of specimens). The RT _NDT(est) from the suggested procedure (or its modifications based on future work) will provide an acceptable alternative to RT _NDT for application of the ASME K _IR curve based on instrumented CVN tests alone. For low-uppershelf steels, the new reference temperature estimate T _0.075 and its correlation to T _0Sch ^dy will provide a methodology for application of MCs to such steels. Further comprehensive work is needed to validate the procedures and correlations suggested in this paper.     

Design of a leucine zipper coiled coil stabilized 1.4 kcal mol-1 by phosphorylation of a serine in the e position

Using a dimeric bZIP protein, we have designed a leucine zipper that becomes more stable after a serine in the e position is phosphorylated by protein kinase A (delta delta GP = -1.4 kcal mol-1 dimer-1 or -0.7 kcal mol-1 residue-1). Mutagenesis studies indicate that three arginines form a network of inter-helical (i,i' + 5; i, i' + 2) and intra-helical (i, i + 4) attractive interactions with the phosphorylated serine. When the arginines are replaced with lysines, the stabilizing effect of serine phosphorylation is reduced (delta delta GP = -0.5 kcal mol-1 dimer-1). The hydrophobic interface of the leucine zipper needs a glycine in the d position to obtain an increase in stability after phosphorylation. The phosphorylated protein binds DNA with a 15-fold higher affinity. Using a transient transfection assay, we document a PKA dependent four-fold activation of a reporter gene. Phosphorylation of a threonine in the same e position decreases the stability by delta delta GP = +1.2 kcal mol-1 dimer-1. We present circular dichroism (CD) thermal denaturations of 15 bZIP proteins before and after phosphorylation. These data provide insights into the structural determinants that result in stabilization of a coiled coil by phosphorylation.     

Study of Aging-Induced Degradation of Fracture Resistance of Alloy 617 Toward High-Temperature Applications

For the Alloy 617, the effect of aging on the fracture energy degradation has been investigated after aging for different time periods at 1023 K (750 °C). A sharp reduction in impact energy (by ~55 pct vis-à-vis the as-received material) after 1000 hours of aging, as evaluated from room-temperature Charpy impact tests, has been observed. Further aging up to 10,000 hours has led to a degradation of fracture energy up to ~78 pct. Fractographic examinations using scanning electron microscopy (SEM) have revealed a change in fracture mode from fibrous-ductile for the un-aged material to intergranular mode for the aged one. The extent of intergranular fracture increases with the increasing aging time, indicating a tendency of the material to undergo grain boundary embrittlement over long-term aging. Analysis of the transmission electron microscopy (TEM) micrographs along with selected area diffraction (SAD) patterns for the samples aged at 10,000 hours revealed finely dispersed γ′ precipitates of size 30 to 40 nm, rich in Al and Ti, along with extensive precipitation of M₂₃C₆ at the grain boundaries. In addition, the presence of Ni₃Si of size in the range of 110 to 120 nm also has been noticed. The extensive precipitation of M₂₃C₆ at the grain boundaries have been considered as a major reason for aging-induced embrittlement of this material.     

Ductile-brittle transition temperatures and dynamic fracture toughness of 9Cr-1Mo steel

The ductile-brittle transition temperature (DBTT) of 9Cr-1Mo steel was characterized by an RT _NDT-based K _IR curve approach and a reference temperature (T ₀)-based master curve (MC) approach. The MC was developed at a dynamic loading condition (loading rate of 5.12 m/s), using precracked Charpy V-notch (PCVN) specimens, and the reference temperature was termed T ₀ ^dy . The RT _NDT and T ₀ ^dy were determined to be −25 °C and −52 °C, respectively. The T ₀ ^dy was also estimated from instrumented CVN tests, using a modified Schindler procedure to evaluate K _Jd ; the result shows close agreement with that obtained from the PCVN tests. The ASME K _IR -curve approach proves to be too conservative compared to the obtained trend of the fracture toughness with temperature. The cleavage fracture stress, σ* _f , estimated from the critical length, l*, shows good agreement with that estimated from the load-temperature diagram (2400 to 2450 MPa), which was constructed from the CVN test results. The crack initiation mechanism has been identified as decohesion of the particle-matrix interface, rather than as the fracture of the particles.