Solving the subset-sum problem with a light-based device

We propose a special computational device which uses light rays for solving the subset-sum problem. The device has a graph-like representation and the light is traversing it by following the routes given by the connections between nodes. The nodes are connected by arcs in a special way which lets us to generate all possible subsets of the given set. To each arc we assign either a number from the given set or a predefined constant. When the light is passing through an arc it is delayed by the amount of time indicated by the number placed in that arc. At the destination node we will check if there is a ray whose total delay is equal to the target value of the subset sum problem (plus some constants).Comment: 14 pages, 6 figures, Natural Computing, 200

NGHIÊN CỨU BIỂU HIỆN TỚI HẠN TRONG CÁC BĂNG HỢP KIM Fe88Co2Zr7B2Cu1

In this work, we investigated the critical behavior of Fe88Co2Zr7B2Cu1 alloy ribbons prepared using a single-roller melt-spinning method. X-ray diffraction analysis shows that the alloy is almost amorphous. This alloy undergoes a second-order ferromagnetic-paramagnetic (FM-PM) phase transition at room temperature (Curie temperature TC = 296 K). To investigate the nature of the FM-PM phase transition near the TC for the alloy, we performed a critical-exponent study. Based on modified Arrott plots, the Kouvel-Fisher method, and Widom’s scaling relation, a set of critical parameters were determined. The critical parameters are β = 0.545 ± 0.041 and γ = 1.109 ± 0.018 obtained from the modified Arrott plots; β = 0.547 ± 0.005 and γ = 1.105 ± 0.016 from the Kouvel-Fisher method, and d = 3.035 ± 0.059 from Widom’s scaling relation. These values are close to those expected for the mean-field model, revealing long-range FM interactions.Trong bài báo này, chúng tôi đã khảo sát biểu hiện tới hạn của băng hợp kim Fe88Co2Zr7B2Cu1 đã được chế tạo bằng phương pháp nguội nhanh. Phép phân tích cấu trúc bằng nhiễu xạ tia X đã cho thấy hợp kim là gần như vô định hình. Hợp kim trải qua chuyển pha loại hai sắt từ-thuận từ (FM-PM) tại nhiệt độ phòng, nhiệt độ chuyển pha Curie TC = 296 K. Để khảo sát bản chất của chuyển pha FM-PM xung quanh TC của hợp kim, chúng tôi đã nghiên cứu các tham số tới hạn. Dựa trên các đồ thị Arrott, phương pháp Kouvel-Fisher và hệ thức Widom, một bộ các tham số tới hạn đã được xác định. Các tham số tới hạn thu được là β = 0.545 ± 0.041, γ = 1.109 ± 0.018 bằng cách sử dụng các đồ thị Arrott, và β = 0.547 ± 0.005, γ = 1.105 ± 0.016 bằng cách sử dụng phương pháp Kouvel-Fisher. Các giá trị thu được là gần với giá trị của mô hình trường trung bình, đặc trưng cho các tương tác sắt từ trật tự xa

Phase formation and magnetocaloric effect in (Pr,Nd)-Fe alloys prepared by rapidly quenched method

In this work, Pr2-xNdxFe17 (x = 0 - 2) ribbons with thickness of about 15 μm were prepared by melt-spinning method. The alloy ribbons were then annealed at different temperatures (900 - 1100°C) for various time (0.25 - 2 h). The formation of the (Pr,Nd)2Fe17 (2:17) crystalline phase in the alloys strongly depends on the Pr/Nd ratio and annealing conditions. Annealing time for the completed formation of the 2:17 phase in the rapidly quenched ribbons is greatly reduced in comparison with that of bulk alloys. Curie temperature, TC, of the alloys can be controlled in room temperature region by changing Pr/Nd ratio. Maximum magnetic entropy change (|ΔSm|max) and full width at haft the maximum peak (FWHM) of the magnetic entropy change of the alloys were respectively found to be larger than 1.5 J.kg−1K−1 and 40 K in room temperature region with magetic field change ΔH = 12 kOe

Investigation of magnetic phase transition and magnetocaloric effect of (Ni,Co)-Mn-Al melt-spun ribbons

Magnetic phase transition, magnetocaloric effect and critical parameters of Ni50-xCoxMn50-yAly (x = 5 and 10; y = 17, 18 and 19) rapidly quenched ribbons have been studied. X-ray diffraction patterns exhibit a coexistence of the L21 and 10M crystalline phases of the ribbons. Magnetization measurements show that all the samples behave as soft magnetic materials with a low coercive force less than 60 Oe. The shape of thermomagnetization curves considerably depends on Co and Al concentrations. The Curie temperature (TC) of the alloy ribbons strongly increases with increasing the Co concentration and slightly decreases with increasing the Al concentration. The Ni45Co5Mn31Al19 and Ni40Co10Mn33Al17 ribbons reveal both the positive and negative magnetocaloric effects. Under magnetic field change (ΔGH) of 13.5 kOe, the maximum magnetic entropy change (|ΔSm|max) of the Ni45Co5Mn31Al19 ribbon is about 2 and -1 J·kg−1·K−1 for negative and positive magnetocaloric effects, respectively. Basing on Arrott - Noakes and Kouvel - Fisher methods, critical parameters of the Ni45Co5Mn31Al19 ribbon were determined to be TC ≈ 290 K, β ≈ 0.58, γ ≈ 0.92 and δ ≈ 2.59. The obtained values of the critical exponents indicate that the magnetic order of the alloy ribbon is close to the mean-field model

Investigation of magnetic phase transition and magnetocaloric effect of (Ni,Co)-Mn-Al melt-spun ribbons

Magnetic phase transition, magnetocaloric effect and critical parameters of Ni50-xCoxMn50-yAly (x = 5 and 10; y = 17, 18 and 19) rapidly quenched ribbons have been studied. X-ray diffraction patterns exhibit a coexistence of the L21 and 10M crystalline phases of the ribbons. Magnetization measurements show that all the samples behave as soft magnetic materials with a low coercive force less than 60 Oe. The shape of thermomagnetization curves considerably depends on Co and Al concentrations. The Curie temperature (TC) of the alloy ribbons strongly increases with increasing the Co concentration and slightly decreases with increasing the Al concentration. The Ni45Co5Mn31Al19 and Ni40Co10Mn33Al17 ribbons reveal both the positive and negative magnetocaloric effects. Under magnetic field change (ΔGH) of 13.5 kOe, the maximum magnetic entropy change (|ΔSm|max) of the Ni45Co5Mn31Al19 ribbon is about 2 and -1 J·kg−1·K−1 for negative and positive magnetocaloric effects, respectively. Basing on Arrott - Noakes and Kouvel - Fisher methods, critical parameters of the Ni45Co5Mn31Al19 ribbon were determined to be TC ≈ 290 K, β ≈ 0.58, γ ≈ 0.92 and δ ≈ 2.59. The obtained values of the critical exponents indicate that the magnetic order of the alloy ribbon is close to the mean-field model

Phase formation and magnetocaloric effect in (Pr,Nd)-Fe alloys prepared by rapidly quenched method

In this work, Pr2-xNdxFe17 (x = 0 - 2) ribbons with thickness of about 15 μm were prepared by melt-spinning method. The alloy ribbons were then annealed at different temperatures (900 - 1100°C) for various time (0.25 - 2 h). The formation of the (Pr,Nd)2Fe17 (2:17) crystalline phase in the alloys strongly depends on the Pr/Nd ratio and annealing conditions. Annealing time for the completed formation of the 2:17 phase in the rapidly quenched ribbons is greatly reduced in comparison with that of bulk alloys. Curie temperature, TC, of the alloys can be controlled in room temperature region by changing Pr/Nd ratio. Maximum magnetic entropy change (|ΔSm|max) and full width at haft the maximum peak (FWHM) of the magnetic entropy change of the alloys were respectively found to be larger than 1.5 J.kg−1K−1 and 40 K in room temperature region with magetic field change ΔH = 12 kOe

Controlling of Conductivity and Morphological Properties of Hole-Transport Layer Using Ionic Liquid for Vacuum-Free Planar Hybrid Solar Cells

In this study, an acidic (A) and pH-neutral (pHN) solution using poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole-transport layer (HTL) was modified using a 1-butyl-3-methylimidazolium chloride (BMIM+Cl−) ionic liquid (IL). The effects of this ionic liquid on the conductivity and morphological properties of the PEDOT:PSS films were investigated. The conductivity and morphological properties of the PEDOT: PSS films before and after adding IL were measured using a UV–vis spectrophotometer and atomic force microscope (AFM), respectively. The conductivity of the A-PEDOT:PSS-film-based ionic liquid was decreased, while the conductivity of the pHN-PEDOT:PSS-film-based ionic liquid was increased. The surface morphology of the A-PEDOT:PSS-film-based ionic liquid was slightly decreased, while the conductivity of the pHN-PEDOT:PSS-film-based ionic liquid was slightly increased. The vacuum-free planar hybrid solar cells (VFPHSCs) using the pHN-PEDOT:PSS-film-based ionic liquid show a higher power conversion efficiency (PCE) than the VFPHSCs using the A-PEDOT:PSS-film-based ionic liquid. We also report that a solar cell with a structure of ITO/pHN-PEDOT:PSS/PTB7:PCBM/PEO/EGaIn has a maximum PCE of about ~5%

Tuning the magnetic phase transition and the magnetocaloric properties of La0.7Ca0.3MnO3 compounds through Sm-doping

In this work, we point out that the width and the nature of the magnetic phase transition, TC value, and as well as magnetocaloric effect in La0.7-xSmxCa0.3MnO3 compounds can be easily modified through Sm-doped into La-site. With an increasing Sm concentration, a systematic decrease in the magnetization, TC, and magnetic entropy change (ΔSm) are observed. The Arrott-plot proveds that the samples with x = 0 and 0.1 undergoing a first-order phase transition. Meanwhile, sample x = 0.2 undergoes a second-order phase transition, which exhibits a high value of the relative cooling power (81.5 J/kg at ΔH = 10 kOe). An analysis of the critical behavior based on the modified Arrott plots method has been done for sample x = 0.2. The results proved a coexistence of the long- and short-range interactions in La0.5Sm0.2Ca0.3MnO3 compound

Conversion of bipolar resistive switching and threshold switching by controlling conductivity behavior and porous volumes of UiO-66 thin films

In the age of big data, a memory with cross-bar array architecture is urgently required to facilitate high-density data storage. To eliminate the sneak path current of integrated circuits, threshold switching-based selectors have been utilized simultaneously with resistive switching memories. In this study, the successful absorption of uric acid (UA) into a UiO-66 matrix was realized at room temperature without any disruption of the host crystalline structure. Fourier transform infrared and Raman spectra revealed the presence of UA based on the interaction of its carbonyl group with the UiO-66 matrix, whereas the diffraction peaks in the X-ray diffraction spectra of the (111) and (200) index planes were slightly shifted to the lower 2θ values, demonstrating the interaction of the UA on the system is occupy porous cages and free volume structures. The occupation of UA in the porous volume of the framework has been estimated by the significant vanishing of surface area from 1299 to 950 cm3 g−1 as well as the almost dismission of UiO-66 porous cages of 12.5 Å by BET analysis. The electronic transitions from linkers to metals and intramolecular between nearest linkers of UA absorbed UiO-66 were heavily reduced via the evidence from photoluminescence spectroscopy. These changes in structural and electronic density lead to the change in the electrical conduction mechanism, operating voltage, and resistive switching characteristics from memory switching to threshold switching corresponding to Ag/UiO-66–PVA/Ag and Ag/UA@UiO-66–PVA/Ag device, respectively. The reduction and vanish of porous cages and free volume restrict the formation management of silver conducting filaments through the UA@UiO-66–PVA matrix. This study provides a new approach to controlling the conversion switching behavior between memory and threshold in metal–organic framework materials for high-density cross-bar architecture

Magnetocaloric effect and critical behavior in Fe-La-Zr rapidly quenched ribbons

Fe90-xLaxZr10 (x = 1 and 2) rapidly quenched ribbons with thickness of about 15 μm were prepared by the melt-spinning method. X-ray diffraction analysis shows that the structure of the ribbons is mostly amorphous. The Curie temperature, TC, of the alloy considerably increased, from ∼262 K for x = 1 to ∼302 K for x = 2, with increasing La-concentration. The maximum magnetic entropy change, |ΔSm|max, of the alloy is about 1.1 J∙kg−1K−1 for a magnetic field change ΔH = 12 kOe. A quite large refrigerant capacity (RC ∼ 74 J∙kg−1 for ΔH = 12 kOe) near the room temperature region is obtained for the alloy. A thorough analysis on critical exponents around the ferromagnetic-paramagnetic phase transition, using the Arrott–Noakes plots and Kouvel–Fisher method, sheds light on the critical magnetic behavior and its association with the magnetocaloric effect in the Fe-La based alloys. Keywords: Magnetocaloric effect, Magnetic refrigerant, Critical parameter, Magnetic entropy change, Melt-spinning metho