A Comprehensive Performance Evaluation of Deformable Face Tracking "In-the-Wild"

Recently, technologies such as face detection, facial landmark localisation and face recognition and verification have matured enough to provide effective and efficient solutions for imagery captured under arbitrary conditions (referred to as "in-the-wild"). This is partially attributed to the fact that comprehensive "in-the-wild" benchmarks have been developed for face detection, landmark localisation and recognition/verification. A very important technology that has not been thoroughly evaluated yet is deformable face tracking "in-the-wild". Until now, the performance has mainly been assessed qualitatively by visually assessing the result of a deformable face tracking technology on short videos. In this paper, we perform the first, to the best of our knowledge, thorough evaluation of state-of-the-art deformable face tracking pipelines using the recently introduced 300VW benchmark. We evaluate many different architectures focusing mainly on the task of on-line deformable face tracking. In particular, we compare the following general strategies: (a) generic face detection plus generic facial landmark localisation, (b) generic model free tracking plus generic facial landmark localisation, as well as (c) hybrid approaches using state-of-the-art face detection, model free tracking and facial landmark localisation technologies. Our evaluation reveals future avenues for further research on the topic.Comment: E. Antonakos and P. Snape contributed equally and have joint second authorshi

Active Metal Brazing and Characterization of Brazed Joints in Titanium to Carbon-Carbon Composites

The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSiI. The joint microstructures were examined using optical microscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint and possible metallurgical bond formation via interdiffusion, which led to good wetting and spreading. A tube-on-plate tensile test was used to evaluate joint strength of Ti-tube/ C-C composite joints. The load-carrying ability was greatest for the Cu-ABA braze joint structures. This system appeared to have the best braze spreading which resulted in a larger braze/C-C composite bonded area compared to the other two braze materials. Also, joint loadcarrying ability was found to be higher for joint structures where the fiber tows in the outer ply of the C-C composite were aligned perpendicular to the tube axis when compared to the case where fiber tows were aligned parallel to the tube axis

Combustion Behaviour of Advanced Solid Propellants.

The study reports the effect of incorporation of Al and ammonium perchlorate (AP) individually and in combination with each other on combustion pattern and specific impulse (Isp) of minimum signature propellants. Incorporation of Al obviates the combustion instability problems; however, it has marginal effect on burning rates. The composition containing AP and zirconium silicate combination gives superior performance; however, its Isp is considerably lower than the composition incorporating 9 per cent AP. A combination of 6 per cent Al gave 20 per cent enhancement in burning rate and 12 s increase in Isp as compared to purely nitramine-based composition, cal-val results also reveal increase in energy output on incorporating AP and Al. Hot stage microscopic and propellant combustion studies indicate occurrence of intense decomposition reaction in case of AP-based compositions

Thermal Behaviour of AP Based CMDB Propellants with Stabilizers

Stability test results and DTA studies indicate the superiority of molecular sieve (MS) over zirconium silicate (ZrSiO/sub 4/) as the stabilizer for a composite modified double base (CMDB) system. Shelf life as computed from autoignition test results was 30 years for MS-based composition which is almost double the life of ZrSiO/sub 4/, but approximately half the life of resorcinol-based composition which was used as a reference. Higher stabilizing effect of MS as compared to ZrSiO/sub 4/ has been explained on the basis of the presence of channels and cavities in its structure, which makes it an effective adsorbent for decomposition catalysing species. Poor stabilization capability of m-dinitrobenzene as compared to resorcinol suggests the catalytic involvement of acidic decomposition products of nitrate esters in autodecomposition process of CMDB propellants

Transition Metal Carbohydrazide Nitrates: Burn-rate Modifiers for Propellants

This paper discusses the synthesis and characterisation of cobalt (Co), nickel (Ni) andcopper (Cu) carbohydrazide nitrates. In differential scanning calorimetry (DSC), the complexesexhibited exothermic decomposition indicating their energetic nature. The commencement ofdecomposition was observed at 220 °C for Ni complex, and at 160 °C for Co complex whereasthat of Cu complex occurred at 75 °C. In view of the better thermal stability, Ni and Co complexeswere selected for further study. The activation energy of decomposition of Ni and Co complexeswere found to be 47 kcal/mol and 60 kcal/mol respectively. Impact and friction sensitivity testresults revealed relatively lower vulnerability of carbohydrazide cobalt nitrate. Its incorporationin an ammonium perchlorate (AP)-based composite propellant led to 9-19 per cent enhancementwhereas that of carbohydrazide nickel nitrate resulted in 28-74 per cent enhancement in burningrates in the pressure range 1.9 MPa to 8.8 MPa. Exothermic decomposition of the coordinationcomplexes on propellant surface and involvement of metal at molecular level formed ondecomposition of the complexes in combustion environment of composite propellant may beattributed to the catalytic effect of this class of compounds on the lines of reported literature

Influence of Various Process Parameters on Mechanical Properties and Ballistics of Nitramine-Based Advanced CMDB Propellants

This paper reports the influence of important process parameters, namely mixing time and batch size; on the mechanical properties and ballistics of nitramine-based advanced CMDB propellants. Considerable improvement to the tune of 67 per cent in tensile strength was observed at a mixing time increase of 60-135 min. Scaling up of batch size from 8 to 25 kg resulted in 30 per cent higher tensile strength. Recorded enhancement of burning rate was of the order of 8 per cent in both the sets of experiments. Ballistically modified composition revealed 11-12 per cent increase in burning rate at all the pressure ranges, on combined increase in mixing time (55 to 85 min) and batch size(5-17kg). These findings are in line with those reported for composite and ballistically modified double-base propellants

Synthesis and Characterisation of Bis-azido Methyl Oxetane and its Polymer and Copolymer with Tetrahydrofuran

Bis-azido methyl oxetane (BAMO) was synthesised from pentaerythritol in two steps. Pentaerythritol was chlorinated to yield a mixture of mono, di, tri and tetra chloro compounds. The trichloro compound on ring closure gives bis-chloro methyl oxetane (BCMO). It was reacted with sodium azide in aqueous medium to obtain BAMO. The latter was polymerised using BF3 etherate catalyst and 1,4-butanediol initiator. Similarly, the BAMO- THF copolymer was also synthesised. All the monomers and polymers were characterised by IR, 1H-NMR, 13C-NMR, and refractive index. The polymers were also characterised for molecular weight, hydroxyl value, etc. Thermal analysis showed that both polymers degrade exothermically with T max of 237 °C for poly BAMO and 241°C for BAMO- THF copolymer with activation energy of 39 kcal/mol and 40 kcal/mol, respectively. Explosive properties like impact and friction sensitivity of BAMO and the other polymers were also determined

Polyurethane Based Inhibition for High Flame Temperature Nitramine Based Composite Modified Double Base propellant

The findings for polypropylene glycol (PPG) and hydroxyl-terminated polybutadiene (HTPB)-based inhibition systems are reported. These findings established that the inhibition system comprising HTPB-IPDI-IDP binder and Sb/sub 2/O/sub 3/-C black filler is most suitable for advanced nitramine-based composite modified double-base propellants in terms of mechanical properties and processibility. The promising composition was characterised for glass-transition behaviour and propellant-inhibition bond strength. Propellant grains inhibited with selected formulations were subjected to static evaluation at extreme temperatures and limited aging studies to obtain data of practical value

Risk-Averse Matchings over Uncertain Graph Databases

A large number of applications such as querying sensor networks, and analyzing protein-protein interaction (PPI) networks, rely on mining uncertain graph and hypergraph databases. In this work we study the following problem: given an uncertain, weighted (hyper)graph, how can we efficiently find a (hyper)matching with high expected reward, and low risk? This problem naturally arises in the context of several important applications, such as online dating, kidney exchanges, and team formation. We introduce a novel formulation for finding matchings with maximum expected reward and bounded risk under a general model of uncertain weighted (hyper)graphs that we introduce in this work. Our model generalizes probabilistic models used in prior work, and captures both continuous and discrete probability distributions, thus allowing to handle privacy related applications that inject appropriately distributed noise to (hyper)edge weights. Given that our optimization problem is NP-hard, we turn our attention to designing efficient approximation algorithms. For the case of uncertain weighted graphs, we provide a $\frac{1}{3}$-approximation algorithm, and a $\frac{1}{5}$-approximation algorithm with near optimal run time. For the case of uncertain weighted hypergraphs, we provide a $\Omega(\frac{1}{k})$-approximation algorithm, where $k$ is the rank of the hypergraph (i.e., any hyperedge includes at most $k$ nodes), that runs in almost (modulo log factors) linear time. We complement our theoretical results by testing our approximation algorithms on a wide variety of synthetic experiments, where we observe in a controlled setting interesting findings on the trade-off between reward, and risk. We also provide an application of our formulation for providing recommendations of teams that are likely to collaborate, and have high impact.Comment: 25 page