The resource theory of dephasing estimation in multiqubit systems

We present a resource theory to investigate the power of a multqubit system as a probe in the task of dephasing estimation. Our approach employs the quantum Fisher information about the dephasing parameter as the resource measure. Based on the monotonicity of quantum Fisher information, we propose two sets of free operations in our resource theory, the Hamming distance preserving operations and the selectively Hamming distance preserving operations. We derive a necessary condition for the state transformation under these free operations and demonstrate that uniform superposition states are the golden states in our resource theory. We further compare our resource theory with the resource theory of coherence and thoroughly investigate the relation between their free operations in both single-qubit and multiqubit cases. Additionally, for multiqubit systems, we discover the incompatibility between the resource theory of dephasing estimation and that of $U(1)$ asymmetry, which is responsible for phase estimation. The condition for enhancing the performance of a probe state in phase estimation while preserving its ability in dephasing estimation is also discussed. Our results provide new insights into quantum parameter estimation by the resource-theoretic approach.Comment: 14 pages, 2 figures. Comments are welcome

Investigation On Premature Failure Of the Self-lubricated Piston Rings in Oil-free Compressor

Abstract: This paper presents the numerical simulation and experimental investigation on impact factors on premature failure of the self-lubricated piston rings in oil-free compressor. In this paper, the finite element method (FEM) was applied to study the non-uniform pressure distributions among the piston rings and the friction process between the self-lubricating piston rings and the cylinder wall, which influence the failure of the self-lubricated piston rings most. In order to verify the mathematic model, a test rig was built to measure the dynamic pressure distributions and temperature field between the piston rings. Both the theoretical and experimental results showed that the first piston ring afford more than 75% of the total pressure difference which was the main reason for the non-uniform wear and thus lead to early invalidation. The friction heat produced between the first piston ring and the cylinder was far more than the rest, which cannot be diffused rapidly through the low conductivity self-lubricating plastics and led to thermal failure of the self-lubricating piston rings. The results provide the theoretical basis to determine the design parameters and the thermal performance of piston rings reasonably

Receptor-Targeting Phthalocyanine Photosensitizer for Improving Antitumor Photocytotoxicity

Photodynamic therapy (PDT) is a promising therapeutic modality which uses a photosensitizer to capture visible light resulting in phototoxicity in the irradiated region. PDT has been used in a number of pathological indications, including tumor. A key desirable feature of the photosensitizer is the high phototoxicity on tumor cells but not on normal cells. In this study, we conjugate a gonadotropin-releasing hormone (GnRH) to a photosensitizer, Zinc phthalocyanine (ZnPc), in order to enhance its specificity to breast cancer, which over-expresses GnRH receptor. ZnPc has unique advantages over other photosensitizers, but is difficult to derivatize and purify as a single isomer. We previously developed a straight-forward way to synthesize mono-substituted β-carboxy-phthalocyanine zinc (ZnPc-COOH). Photophysical and photochemical parameters of this ZnPc-GnRH conjugate including fluorescence quantum yield (Фf), fluorescence decay time (τs) and singlet oxygen quantum yield (ФΔ) were evaluated and found comparable with that of ZnPc, indicating that addition of a GnRH peptide does not significantly alter the generation of singlet oxygen from ZnPc. Cellular uptakes and phototoxicities of this conjugate were tested and found significantly enhanced on human breast cancer cell lines overexpressing GnRH receptors (MDA-MB-231 and MCF-7 cells) compared to cells with low levels of GnRH receptors, such as human embryonic lung fibroblast (HELF) and human liver carcinoma (HepG2) cells. In addition, the cellular uptake of this conjugate toward MCF-7 cells were found clearly alleviated by a GnRH receptor blocker Cetrorelix, suggesting that the cellular uptake of this conjugate was GnRH receptor-mediated. Put together, these findings revealed that coupling ZnPc with GnRH analogue was an effective way to improve the selectivity of ZnPc towards tumors with over-expressed GnRH receptors

Study on the Effects of Vane Parameters on Separation Performance in an Axial Flow Cyclone Separator

The oil-gas cyclone separator is a key component to an oil injection compressor system for its advantages of small volume, simple structure, high separation efficiency and low pressure loss. This paper presents the investigation on new type axial flow cyclone separator performance under different structural parameters, including the angle of vanes, the number of vanes, the rotation angle of single vane, by numerical simulation and verification experiments. A numerical model of two-phase flow in the cyclone separator was established and the separation efficiency and pressure loss of cyclone separators were simulated. A test rig was built and the diameter distributions of droplets at the inlet and outlet of separator were measured by a Malvern laser particle size analyzer to verify the simulation model. The results showed that the separation efficiency and pressure loss can be improved with the increase of the rotation angle of vanes. With the decrease of the outlet angle of the first stage vane and the increase of the number of vanes, the critical separated droplet diameter of separator can be lowered effectively. The results showed that the optimum outlet angle of vanes is 22°~25° considering the separation efficiency and the pressure loss of separators

SEGA: Structural Entropy Guided Anchor View for Graph Contrastive Learning

In contrastive learning, the choice of ``view'' controls the information that the representation captures and influences the performance of the model. However, leading graph contrastive learning methods generally produce views via random corruption or learning, which could lead to the loss of essential information and alteration of semantic information. An anchor view that maintains the essential information of input graphs for contrastive learning has been hardly investigated. In this paper, based on the theory of graph information bottleneck, we deduce the definition of this anchor view; put differently, \textit{the anchor view with essential information of input graph is supposed to have the minimal structural uncertainty}. Furthermore, guided by structural entropy, we implement the anchor view, termed \textbf{SEGA}, for graph contrastive learning. We extensively validate the proposed anchor view on various benchmarks regarding graph classification under unsupervised, semi-supervised, and transfer learning and achieve significant performance boosts compared to the state-of-the-art methods.Comment: ICML'2

Study of deformation law and support design feasibility of right-angled trapezoidal roadways

Given the problems of serious asymmetric deformation and the difficulty in supporting right-angled trapezoidal roadways during the mining process, we established a mechanical model of surrounding rock for a right-angled trapezoidal roadway, determined the relationship between the deflection and tilt angle of the roadway roof, and determined that the typical failure mode of right-angled trapezoidal roadways is the upper slip of the high side. Two optimized support schemes are proposed, in which a constant resistance large deformation (CRLD) bolt + ordinary I-steel or a portal energy absorbing hydraulic (PEAH) support + ordinary bolt is used as the main support instead of an ordinary bolt + ordinary I-steel. Numerical simulation analysis shows that the aforementioned optimized support schemes can reduce the deformation, acoustic emission (AE) quantity, and AE energy of rock surrounding roadways and change how surrounding rock releases energy from main earthquake type to swarm earthquake type. The support scheme with CRLD bolt + ordinary I-steel or PEAH support + ordinary bolt as the main support can reduce the deformation of a roadway’s high side to 0.192 and 0.145 m, respectively. This shows that the two optimized schemes can effectively improve the overall bearing capacity and integrity of the rock surrounding roadways, which can be applied in the field

Effects of Surface Coating Preparation and Sliding Modes on Titanium Oxide Coated Titanium Alloy for Aerospace Applications

This paper investigates the mechanical response of a coated Ti-6Al-4V alloy surface under different sliding contact stress conditions. The surface was coated with an oxide ceramic material created through the use of a recently developed technique known as plasma electrolytic oxidation (PEO). During the PEO procedure, a composition of silicate and phosphate was used as the electrolyte. In order to evaluate the coating, pin-on-disk (POD) tribology tests and cyclic inclined sliding tests were used under dry room conditions. Furthermore, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to examine the morphology and composition of the coating surfaces. The results of the POD tests revealed that the PEO coating could have a low coefficient of friction and suggested that high silicon concentrations in the PEO coatings take away oxygen from stoichiometric Ti oxides to create lubricating oxides. In addition, cyclic inclined sliding tests showed that smaller pores on the surface of the coating could permit a higher coating cohesive strength and allow the coated Ti alloy surface to perform better under high inclined sliding forces