Matrix Product Representation of Locality Preserving Unitaries

The matrix product representation provides a useful formalism to study not only entangled states, but also entangled operators in one dimension. In this paper, we focus on unitary transformations and show that matrix product operators that are unitary provides a necessary and sufficient representation of 1D unitaries that preserve locality. That is, we show that matrix product operators that are unitary are guaranteed to preserve locality by mapping local operators to local operators while at the same time all locality preserving unitaries can be represented in a matrix product way. Moreover, we show that the matrix product representation gives a straight-forward way to extract the GNVW index defined in Ref.\cite{Gross2012} for classifying 1D locality preserving unitaries. The key to our discussion is a set of `fixed point' conditions which characterize the form of the matrix product unitary operators after blocking sites. Finally, we show that if the unitary condition is relaxed and only required for certain system sizes, the matrix product operator formalism allows more possibilities than locality preserving unitaries. In particular, we give an example of a simple matrix product operator which is unitary only for odd system sizes, does not preserve locality and carries a `fractional' index as compared to their locality preserving counterparts.Comment: 14 page

Optimizing semiconductor devices by self-organizing particle swarm

A self-organizing particle swarm is presented. It works in dissipative state by employing the small inertia weight, according to experimental analysis on a simplified model, which with fast convergence. Then by recognizing and replacing inactive particles according to the process deviation information of device parameters, the fluctuation is introduced so as to driving the irreversible evolution process with better fitness. The testing on benchmark functions and an application example for device optimization with designed fitness function indicates it improves the performance effectively.Comment: Congress on Evolutionary Computation, 2004. CEC2004. Volume: 2, On page(s): 2017- 2022 Vol.

In vivo contrast free chronic myocardial infarction characterization using diffusion-weighted cardiovascular magnetic resonance.

BackgroundDespite the established role of late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in characterizing chronic myocardial infarction (MI), a significant portion of chronic MI patients are contraindicative for the use of contrast agents. One promising alternative contrast free technique is diffusion weighted CMR (dwCMR), which has been shown ex vivo to be sensitive to myocardial fibrosis. We used a recently developed in vivo dwCMR in chronic MI pigs to compare apparent diffusion coefficient (ADC) maps with LGE imaging for infarct characterization.MethodsIn eleven mini pigs, chronic MI was induced by complete occlusion of the left anterior descending artery for 150 minutes. LGE, cine, and dwCMR imaging was performed 8 weeks post MI. ADC maps were derived from three orthogonal diffusion directions (b = 400 s/mm2) and one non-diffusion weighted image. Two semi-automatic infarct classification methods, threshold and full width half max (FWHM), were performed in both LGE and ADC maps. Regional wall motion (RWM) analysis was performed and compared to ADC maps to determine if any observed ADC change was significantly influenced by bulk motion.ResultsADC of chronic MI territories was significantly increased (threshold: 2.4 ± 0.3 μm2/ms, FWHM: 2.4 ± 0.2 μm2/ms) compared to remote myocardium (1.4 ± 0.3 μm2/ms). RWM was significantly reduced (threshold: 1.0 ± 0.4 mm, FWHM: 0.9 ± 0.4 mm) in infarcted regions delineated by ADC compared to remote myocardium (8.3 ± 0.1 mm). ADC-derived infarct volume and location had excellent agreement with LGE. Both LGE and ADC were in complete agreement when identifying transmural infarcts. Additionally, ADC was able to detect LGE-delineated infarcted segments with high sensitivity, specificity, PPV, and NPV. (threshold: 0.88, 0.93, 0.87, and 0.94, FWHM: 0.98, 0.97, 0.93, and 0.99, respectively).ConclusionsIn vivo diffusion weighted CMR has potential as a contrast free alternative for LGE in characterizing chronic MI

Handling boundary constraints for numerical optimization by particle swarm flying in periodic search space

The periodic mode is analyzed together with two conventional boundary handling modes for particle swarm. By providing an infinite space that comprises periodic copies of original search space, it avoids possible disorganizing of particle swarm that is induced by the undesired mutations at the boundary. The results on benchmark functions show that particle swarm with periodic mode is capable of improving the search performance significantly, by compared with that of conventional modes and other algorithms.Comment: Congress on Evolutionary Computation, 2004. CEC2004. Volume: 2, On page(s): 2307- 2311 Vol.

Response of reinforced mortar‑less interlocking brick wall under seismic loading

Mortar-less construction with interlocking bricks has many advantages, such as improved construction efficiency and relatively low requirements on labour skills. Nevertheless, the seismic performance of interlocking brick structures is not well understood yet. In this paper, laboratory tests and numerical modelling are carried out to investigate the seismic behaviour of interlocking brick walls. Laboratory shaking table tests are performed on a scaled reinforced mortar-less interlocking brick wall. The response and damage modes under in-plane seismic loading are investigated. A detailed numerical model is then generated and validated with the laboratory testing data. Unlike the conventional masonry wall that diagonal shear damage governs the failure, the interlocking brick wall exhibits rocking responses, whose damage is mainly at the two bottom corners of the wall. Full-scale interlocking brick walls are then modelled and compared with conventional concrete masonry unit (CMU) walls bonded by mortar. Comparisons are made between the seismic resistances and damage modes of the two walls. The influences of ground motion intensities, vertical components of seismic excitations and different seismic time histories on the seismic behaviour of the interlocking brick wall are examined. It is found that the interlocking brick wall has a higher seismic resistance capacity than the conventional CMU wall. Inter-brick friction is the main energy dissipation mechanism in the interlocking brick wall. Because of the rocking response, vertical component of the ground motion significantly influences the damage of interlocking brick wall. The interlocking brick wall is insensitive to velocity pulses of ground motions due to its relatively high natural frequency