(E)-1-Bromo-4-(2-nitro­prop-1-en­yl)benzene

The title compound, C9H8BrNO2, which was synthesized by the condensation of 4-bromo­benzaldehyde with nitro­ethane, possesses a trans configuration. The dihedral angle between the benzene ring and the mean plane of the double bond is 7.31 (3)°. The crystal structure is stabilized by short inter­molecular Br⋯O contacts [3.168 (4) Å]

Sparticle spectrum and dark matter in type I string theory with an intermediate scale

The supersymmetric particle spectrum is calculated in type I string theories formulated as orientifold compactifications of type IIB string theory. A string scale at an intermediate value of $10^{11}-10^{12}$ GeV is assumed and extra vector-like matter states are introduced to allow unification of gauge coupling constants to occur at this scale. The qualitative features of the spectrum are compared with Calabi-Yau compactification of the weakly coupled heterotic string and with the eleven dimensional supergravity limit of $M$-theory. Some striking differences are observed. Assuming that the lightest neutralino provides the dark matter in the universe, further constraints on the sparticle spectrum are obtained. Direct detection rates for dark matter are estimated.Comment: LaTeX file (10 pages+10 figures), improved references, v3: typos fixed, accepted for publication in Physics Letters

Supersymmetric Pati-Salam Models from Intersecting D6-branes: A Road to the Standard Model

We provide a systematic construction of three-family N=1 supersymmetric Pati-Salam models from Type IIA orientifolds on \IT^6/(\IZ_2\times \IZ_2) with intersecting D6-branes. All the gauge symmetry factors $SU(4)_C\times SU(2)_L \times SU(2)_R$ arise from the stacks of D6-branes with U(n) gauge symmetries, while the ``hidden sector'' is specified by $USp(n)$ branes, parallel with the orientifold planes or their ${\bf Z_2}$ images. The Pati-Salam gauge symmetry can be broken down to the $SU(3)_C\times SU(2)_L\times U(1)_{B-L} \times U(1)_{I_{3R}}$ via D6-brane splittings, and further down to the Standard Model via D- and F-flatness preserving Higgs mechanism from massless open string states in a N=2 subsector. The models also possess at least two confining hidden gauge sectors, where gaugino condensation can in turn trigger supersymmetry breaking and (some) moduli stabilization. The systematic search yields 11 inequivalent models: 8 models with less than 9 Standard model Higgs doublet-pairs and 1 model with only 2 Standard Model Higgs doublet-pairs, 2 models possess at the string scale the gauge coupling unification of $SU(2)_L$ and $SU(2)_R$, and all the models possess additional exotic matters. We also make preliminary comments on phenomenological implications of these models.Comment: RevTeX4, 48 pages, 18 tables, typos fixed, added comments on confinement of massless chiral exotics, accepted for publication in Nucl. Phys.

Can we distinguish SUSY breaking terms between weakly and strongly coupled heterotic string theories ?

We study soft SUSY breaking terms in heterotic M-theory. We show that both weakly and strongly coupled heterotic string models lead to the same relations of soft SUSY breaking terms, $A=-M$ and $m^2 = M^2/3$, up to $O((\alpha T/S)^2)$.Comment: 11 pages, late

An Iterated Greedy Algorithm for a Parallel Machine Scheduling Problem with Re-entrant and Group Processing Features

This research paper addresses a novel parallel machine scheduling problem with re-entrant and group processing features, specifically motivated by the hot milling process in the modern steel manufacturing industry. The objective is to minimize the makespan. As no existing literature exists on this problem, the paper begins by analyzing the key characteristics of the problem. Subsequently, a mixed integer linear programming model is formulated. To tackle the problem, an improved iterated greedy algorithm (IGA) is proposed. The IGA incorporates a problem-specific heuristic to construct the initial solution. Additionally, it incorporates an effective destruction and reconstruction procedure. Furthermore, an acceptance rule is developed to prevent the IGA from getting stuck in local optima. The proposed approach is evaluated through computational experiments. The results demonstrate that the proposed IGA outperforms three state-of-the-art meta-heuristics, highlighting its high effectiveness. Overall, this research contributes to the understanding and solution of the parallel machine scheduling problem with re-entrant and group processing features in the context of the hot milling process. The proposed algorithm provides insights for practical applications in the steel manufacturing industry

Integrating the Symmetry Image and Improved Sparse Representation for Railway Fastener Classification and Defect Recognition

The detection of fastener defects is an important task for ensuring the safety of railway traffic. The earlier automatic inspection systems based on computer vision can detect effectively the completely missing fasteners, but they have weaker ability to recognize the partially worn ones. In this paper, we propose a method for detecting both partly worn and completely missing fasteners, the proposed algorithm exploits the first and second symmetry sample of original testing fastener image and integrates them for improved representation-based fastener recognition. This scheme is simple and computationally efficient. The underlying rationales of the scheme are as follows: First, the new virtual symmetrical images really reflect some possible appearance of the fastener; then the integration of two judgments of the symmetrical sample for fastener recognition can somewhat overcome the misclassification problem. Second, the improved sparse representation method discarding the training samples that are “far” from the test sample and uses a small number of samples that are “near” to the test sample to represent the test sample, so as to perform classification and it is able to reduce the side-effect of the error identification problem of the original fastener image. The experimental results show that the proposed method outperforms state-of-the-art fastener recognition methods

Quasi-Supersymmetric G3G^3 Unification from Intersecting D6-Branes on Type IIA Orientifolds

We construct three quasi-supersymmetric $G^3$ GUT models with $S_3$ symmetry and gauge coupling unification from intersecting D6-branes on Type IIA orientifolds. The Standard Model fermions and Higgs doublets can be embedded into the bifundamental representations in these models, and there is no any other unnecessary massless representation. Especially in Model I with gauge group $U(4)^3$, we just have three-family SM fermions and three pairs of Higgs particles. The $G^3$ gauge symmetry in these models can be broken down to the Standard Model gauge symmetry by introducing light open string states. And 1 TeV scale supersymmetry breaking soft masses imply the reasonable intermediate string scale.Comment: Latex, 14 pages, typos fixed, version to appear in PL

D6-brane Splitting on Type IIA Orientifolds

We study the open-string moduli of supersymmetric D6-branes, addressing both the string and field theory aspects of D6-brane splitting on Type IIA orientifolds induced by open-string moduli Higgsing (i.e., their obtaining VEVs). Specifically, we focus on the Z_2 x Z_2 orientifolds and address the symmetry breaking pattern for D6-branes parallel with the orientifold 6-planes as well as those positioned at angles. We demonstrate that the string theory results, i.e., D6-brane splitting and relocating in internal space, are in one to one correspondence with the field theory results associated with the Higgsing of moduli in the antisymmetric representation of Sp(2N) gauge symmetry (for branes parallel with orientifold planes) or adjoint representation of U(N) (for branes at general angles). In particular, the moduli Higgsing in the open-string sector results in the change of the gauge structure of D6-branes and thus changes the chiral spectrum and family number as well. As a by-product, we provide the new examples of the supersymmetric Standard-like models with the electroweak sector arising from Sp(2N)_L x Sp(2N)_R gauge symmetry; and one four-family example is free of chiral Standard Model exotics.Comment: 44 pages, 7 figures; The anomaly-free models in Subsections 4.2 and 4.3 presented, references added, typos fixe

CofiFab: Coarse-to-fine fabrication of large 3D objects

This paper presents CofiFab, a coarse-to-fine 3D fabrication solution, which combines 3D printing and 2D laser cutting for cost-effective fabrication of large objects at lower cost and higher speed. Our key approach is to first build coarse internal base structures within the given 3D object using laser-cutting, and then attach thin 3D-printed parts, as an external shell, onto the base to recover the fine surface details. CofiFab achieves this with three novel algorithmic components. First, we formulate an optimization model to compute fabricatable polyhedrons of maximized volume, as the geometry of the internal base. Second, we devise a new interlocking scheme to tightly connect laser-cut parts into a strong internal base, by iteratively building a network of nonorthogonal interlocking joints and locking parts around polyhedral corners. Lastly, we also optimize the partitioning of the external object shell into 3D-printable parts, while saving support material and avoiding overhangs. These components also consider aesthetics, stability and balancing in addition to cost saving. As a result, CofiFab can efficiently produce large objects by assembly. To evaluate its effectiveness, we fabricate objects of varying shapes and sizes, where CofiFab significantly improves compared to previous methods

M-theory dark matter

The phenomenological implications of the eleven dimensional limit of $M$-theory (strongly coupled $E_8\times E_8$) are investigated. In particular we calculate the supersymmetric particle spectrum subject to constraints of correct electroweak symmetry breaking and the requirement that the lightest supersymmetric particle provides the dark matter of the universe. We also calculate direct detection event rates of the lightest neutralino relevant for non-baryonic dark matter experiments. The modulation effect, due to Earth's annual motion is also calculated.Comment: LaTeX file, 30 pages including 12 figures;v2 typos fixed and references adde