Joint Separable and Non-Separable Transforms for Next-Generation Video Coding

Throughout the past few decades, the separable Discrete Cosine Transform (DCT), particularly the DCT type II, has been widely used in image and video compression. It is well known that, under first-order stationary Markov conditions, DCT is an efficient approximation of the optimal Karhunen-Loève transform. However, for natural image and video sources, the adaptivity of a single separable transform with fixed core is rather limited for the highly dynamic image statistics, e.g., textures and arbitrarily directed edges. It is also known that non-separable transforms can achieve better compression efficiency for images with directional texture patterns, yet they are computationally complex, especially when the transform size is large. In order to achieve higher transform coding gains with relatively low-complexity implementations, we propose a joint separable and non-separable transform. The proposed separable primary transform, named Enhanced Multiple Transform (EMT), applies multiple transform cores from a pre-defined subset of sinusoidal transforms, and the transform selection is signaled in a joint block level manner. Moreover, a Non-Separable Secondary Transform (NSST) method is proposed to operate in conjunction with EMT. Unlike the existing non-separable transform schemes which require excessive amounts of memory and computation, the proposed NSST efficiently improves coding gain with much lower complexity. Extensive experimental results show that the proposed methods, in a state-of-the-art video codec, such as HEVC, can provide significant coding gains (average 6.9% and 4.5% bitrate reductions for intra and random-access coding, respectively).

Mitigation of Lightning Hazards at the More Sensitive Points in Wind Farms Using Ant-Colony Optimization Technique

The lightning energy can be very harmfull to the wind turbine farm components. This paper attempts to evaluate the overvoltages at the sensitive points in wind farm, using ATP-EMTP package program. Four cases were performed; a) the transient voltage distribution in the insulating layer of the control line, b) the transient voltage on the control equipment, c) the coupling voltage between the tower and the control, and, d) the transient voltage distribution in the wind turbine WT generator, boast transformers and grid. These cases were performed under different lightning current conditions and at conventional design and proper design of grounding system. The results show that the ground potential rise (GPR) is reduced with using the proper design of wind turbine ground system, but the induced voltage at the control system will not affected. This work determines the optimum location of wind turbine at the areas of maximum lightning incidence. Ant colony optimization (ACO) technique is implemented to find the optimum wind farm location. This work enhances the protection strategy of the wind farms against lightning stroke.

Ferromagnetic exchange anisotropy from antiferromagnetic superexchange in the mixed 3d-5d transition-metal compound Sr3CuIrO6

We report a combined experimental and theoretical study of the unusual ferromagnetism in the one-dimensional copper-iridium oxide Sr(3)CuIrO(6). Utilizing Ir L(3) edge resonant inelastic x-ray scattering, we reveal a large gap magnetic excitation spectrum. We find that it is caused by an unusual exchange anisotropy generating mechanism, namely, strong ferromagnetic anisotropy arising from antiferromagnetic superexchange, driven by the alternating strong and weak spin-orbit coupling on the 5d Ir and 3d Cu magnetic ions, respectively. From symmetry consideration, this novel mechanism is generally present in systems with edge-sharing Cu(2+)O(4) plaquettes and Ir(4+)O(6) octahedra. Our results point to unusual magnetic behavior to be expected in mixed 3d-5d transition-metal compounds via exchange pathways that are absent in pure 3d or 5d compounds.

Testing the validity of the strong spin-orbit-coupling limit for octahedrally coordinated iridate compounds in a model system Sr3CuIrO6

The electronic structure of Sr3CuIrO6, a model system for the 5d Ir ion in an octahedral environment, is studied through a combination of resonant inelastic x-ray scattering and theoretical calculations. Resonant inelastic x-ray scattering spectra at the Ir L3 edge reveal an Ir t(2g) manifold that is split into three levels, in contrast to the expectations of the strong spin-orbit-coupling limit. Effective Hamiltonian and ab inito quantum chemistry calculations find a strikingly large noncubic crystal field splitting comparable to the spin-orbit coupling, which results in a strong mixing of the j(eff)=1/2 and j(eff)=3/2 states and modifies the isotropic wave functions on which many theoretical models are based.

A blind algorithm for reverberation-time estimation using subband decomposition of speech signals

An algorithm for blind estimation of reverberation time (RT) in speech signals is proposed. Analysis is restricted to the free-decaying regions of the signal, where the reverberation effect dominates, yielding a more accurate RT estimate at a reduced computational cost. A spectral decomposition is performed on the reverberant signal and partial RT estimates are determined in all signal subbands, providing more data to the statistical-analysis stage of the algorithm, which yields the final RT estimate. Algorithm performance is assessed using two distinct speech databases, achieving 91% and 97% correlation with the RTs measured by a standard nonblind method, indicating that the proposed method blindly estimates the RT in a reliable and consistent manner.

Optimising the care of patients with cirrhosis and gastrointestinal haemorrhage: a quality improvement study

BACKGROUND

Patients with cirrhosis and gastrointestinal haemorrhage are a complex group with high thirty-day mortality rates.

AIM

To evaluate the quality of care delivered to patients admitted with gastrointestinal (GI) haemorrhage to a tertiary care centre before and after implementing a quality improvement initiative for better adherence to practice standards.

METHODS

This is a prospective cohort study. All patients admitted to a tertiary care centre with a GI haemorrhage and known or suspected chronic liver disease were evaluated before and after the quality improvement initiative was implemented. Interventions to improve quality of care included the delivery of educational sessions for medical practitioners, and creation and implementation of standardised admission order sets. Quality of care measures included delivery of prophylactic antibiotics (PAs) within 24 h of admission, delivery of a somatostatin analogue (SA) and use of a proton pump inhibitor (PPI); optimal care was defined as receiving all three. Secondary outcomes included hospital length of stay (LOS) and 30-day readmission rate.

RESULTS

In comparing the preintervention and postintervention groups, we found significant gains in delivering PAs (57% vs. 75%, P=0.05), SAs (54% vs. 76%, P=0.013) and overall optimal care (41% vs. 65%, P=0.008). Use of PPIs did not change and remained in accordance with guidelines (90% vs. 87%, P=0.67). Hospital LOS remained similar between the two groups (6.8 vs. 7.1, P=0.88), whereas the 30-day readmission decreased (41% vs. 13%, P=0.001).

CONCLUSION

Implementation of quality improvement initiatives, such as targeted educational efforts and standardised order sets, can improve the quality of care delivered and patient outcomes in patients with cirrhosis and GI haemorrhage.