Spotting Difficult Weakly Correlated Binary Knapsack Problems

In this paper, we examine the possibility of quickly deciding whether or not an instance of a binary knapsack problem is difficult for branch and bound algorithms. We first observe that the distribution of the objective function values is smooth and unimodal. We define a measure of difficulty of solving knapsack problems through branch and bound algorithms, and examine the relationship between the degree of correlation between profit and cost values, the skewness of the distribution of objective function values and the difficulty in solving weakly correlated binary knapsack problems. We see that the even though it is unlikely that an exact relationship exists for individual problem instances, some aggregate relationships may be observed. Key words: Binary Knapsack Problems; Skewness; Computational Experiments.

Percolative switching in transition metal dichalcogenide field-effect transistors at room temperature

We have addressed the microscopic transport mechanism at the switching or on-off transition in transition metal dichalcogenide (TMDC) field-effect transistors (FET), which has been a controversial topic in TMDC electronics, especially at room temperature. With simultaneous measurement of channel conductivity and its slow time-dependent fluctuation (or noise) in ultra-thin WSe2 and MoS2 FETs on insulating SiO2 substrates, where noise arises from McWhorter-type carrier number fluctuations, we establish that the switching in conventional backgated TMDC FETs is a classical percolation transition in a medium of inhomogeneous carrier density distribution. From the experimentally observed exponents in the scaling of noise magnitude with conductivity, we observe unambiguous signatures of percolation in random resistor network, particularly in WSe2 FETs close to switching, which crosses over to continuum percolation at a higher doping level. We demonstrate a powerful experimental probe to the microscopic nature of near-threshold electrical transport in TMDC FETs, irrespective of the material detail, device geometry or carrier mobility, which can be extended to other classes of 2D material-based devices as well

MODELING OF AN AIR-BASED DENSITY SEPARATOR

There is a lack of fundamental studies by means of state of the art numerical and scale modeling techniques scrutinizing the theoretical and technical aspect of air table separators as well as means to comprehend and improve the efficiency of the process. The dissertation details the development of a workable empirical model, a numerical model and a scale model to demonstrate the use of a laboratory air table unit. The modern air-based density separator achieves effective density-based separation for particle sizes greater than 6 mm. Parametric studies with the laboratory scale unit using low rank coal have demonstrated the applicability with regards to finer size fractions of the range 6 mm to 1 mm. The statistically significant empirical models showed that all the four parameters, i.e, blower and table frequency, longitudinal and transverse angle were significant in determining the separation performance. Furthermore, the tests show that an increase in the transverse angle increased the flow rate of solids to the product end and the introduction of feed results in the dampening of airflow at the feed end. The higher table frequency and feed rate had a detrimental effect on the product yield due to low residence time of particle settlement. The research further evaluated fine particle upgrading using various modeling techniques. The numerical model was evaluated using K-Epsilon and RSM turbulence formulations and validated using experimental dataset. The results prove that the effect of fine coal vortices forming around the riffles act as a transport mechanism for higher density particle movement across the table deck resulting in 43% displacement of the midlings and 29% displacement of the heavies to the product side. The velocity and vector plots show high local variance of air speeds and pressure near the feed end and an increase in feed rate results in a drop in deshaling capability of the table. The table was further evaluated using modern scale-modeling concepts and the scaling laws indicated that the vibration velocity has an integral effect on the separation performance. The difference between the full-scale model and the scaled prototype was 3.83% thus validating the scaling laws

Determining the space-time structure of bottom-quark couplings to spin-zero particles

We present a general argument that highlights the difficulty of determining the space-time structure of the renormalizable bottom quark Yukawa interactions of the Standard Model Higgs boson, or for that matter of any hypothetical spin-zero particle, at high energy colliders. The essence of the argument is that, it is always possible, by chiral rotations, to transform between scalar and pseudoscalar Yukawa interactions without affecting the interactions of bottom quarks with SM gauge bosons. Since these rotations affect only the $b$-quark mass terms in the Standard Model Lagrangian, any differences in observables for scalar versus pseudoscalar couplings vanish when $m_b \rightarrow 0$, and are strongly suppressed in high energy processes involving the heavy spin-zero particle where the $b$-quarks are typically relativistic. We show, however, that the energy dependence of, for instance, $e^+e^- \rightarrow b\bar{b} X$ (here $X$ denotes the spin-zero particle) close to the reaction threshold may serve to provide a distinction between the scalar versus pseudoscalar coupling at electron-positron colliders that are being proposed, provided that the $Xb\bar{b}$ coupling is sizeable. We also note that while various kinematic distributions for $t \bar{t} h$ are indeed sensitive to the space-time structure of the top Yukawa coupling, for a spin-0 particle $X$ of an arbitrary mass, the said sensitivity is lost if $m_{X} >> m_t$.Comment: 18 [ages, 6 figure

G221 Interpretations of the Diboson and Wh Excesses

Based on an $SU(2) \times SU(2) \times U(1)$ effective theory framework (aka $G221$ models), we investigate a leptophobic $SU(2)_L \times SU(2)_R \times U(1)_{B-L}$ model, in which the right-handed $W^\prime$ boson has the mass of around 2 TeV, and predominantly couples to the standard model quarks and the gauge-Higgs sector. This model could explain the resonant excesses near 2 TeV reported by the ATLAS collaboration in the $WZ$ production decaying into hadronic final states, and by the CMS collaboration in the $Wh$ channel decaying into $b\bar{b}\ell\nu$ and dijet final state. After imposing the constraints from the electroweak precision and current LHC data, we find that to explain the three excesses in $WZ$, $Wh$ and dijet channels, the $SU(2)_R$ coupling strength $g_R$ favors the range of $0.47 \sim 0.68$. In this model, given a benchmark 2 TeV $W'$ mass, the $Z'$ mass is predicted to be around $2.9$ TeV if the doublet Higgs (LPD) is used to break the G221 symmetry, consistent with the 2.9 TeV $e^+e^-$ event recently observed at CMS. A $3 \sim 5$ TeV mass is typically predicted for the triplet Higgs (LPT) symmetry breaking scenario, can also be consistent with a 2.9 TeV dilepton signal. These signatures can be further explored by the LHC Run-2 data.Comment: 16 pages, 6 figures, revised version 2. With a 2.9 TeV Z' event observed in CMS, we updated our paper by discussing the possible 2.9 TeV Z' signature together with the 2 TeV W' exces

Interplay among gravitational waves, dark matter and collider signals in the singlet scalar extended type-II seesaw model

We study the prospect of simultaneous explanation of tiny neutrino masses, dark matter (DM), and the observed baryon asymmetry of the Universe in a $Z_3$-symmetric complex singlet scalar extended type-II seesaw model. The complex singlet scalar plays the role of DM. Analyzing the thermal history of the model, we identify the region of the parameter space that can generate a first-order electroweak phase transition (FOEWPT) in the early Universe, and the resulting stochastic gravitational waves (GW) can be detected at future space/ground-based GW experiments. First, we find that light triplet scalars do favor an FOEWPT. In our study, we choose the type-II seesaw part of the parameter space in such a way that light triplet scalars, especially the doubly charged ones, evade the strong bounds from their canonical searches at the Large Hadron Collider (LHC). However, the relevant part of the parameter space, where FOEWPT can happen only due to strong SM doublet-triplet interactions, is in tension with the SM-like Higgs decay to a pair of photons, which has already excluded the bulk of this parameter space. On the other hand, the latest spin-independent DM direct detection constraints from XENON-1T and PANDA-4T eliminate a significant amount of parameter space relevant for the dark sector assisted FOEWPT scenarios, and it is only possible when the complex scalar DM is significantly underabundant. In short, we conclude from our analysis that the absence of new physics at the HL-LHC and/or various DM experiments in the near future will severely limit the prospects of detecting a stochastic GW at future GW experiments and will exclude the possibility of electroweak baryogenesis within this model.Comment: 62 pages, 18 figures, 8 tables. Matches version accepted for publication in JHE

Application of geographical information system in understanding the accessibility and utilization primary health centres: a district level study of rural India

Health is an important indicator to determine the overall development of a Country. Disease free nation leads to high level of productivity of human being and so it is an important element. This disease free nation can be attained by improving the health and nutritional status of the population. One of the ways of achieving it, is through improved access to and utilization of health services with special focus on the underserved and under privileged segment of population. Fortunately, the health care services in India are equivalently provided to all, ignoring the caste, color, creed and sex. The task of accessibility can be attained by establishing sub centers, primary health centers, community health centers and hospitals in remote and inaccessible areas. Primary health centers are an effective way of delivering health care in the rural areas. It is an imperative strategy to provide "Health For AH" and is widely acknowledged as a universal solution for improving well being of population in the world. The present study focuses on the evaluating the status of accessibility and utilization of health care facilities in the second highest populated country of the world. The number and type of barriers to accessibility of primary health centers differ from country to country and time to time. Affordability, acceptability and accommodation are the three non spatial barriers to the utilization and accessibility are spatial in context. Availability in context to PHC refers to the number of health care service points and accessibility is travel impedance i.e., distance or time between the residential or demand areas and PHC. In this paper, availability and accessibility are considered as spatial accessibility and the aim is to determine if PHC's are equitably distributed in the Nadia District of West Bengal state of India. The future allocation of the lowest order central facility is done with the help of Geographical Information Centre