Fuzzy Proportional Integral Derivative control of a voice coil actuator system for adaptive deformable mirrors

Research on adaptive deformable mirror technology for voice coil actuators(VCAs)is an important trend in the development of large ground-based telescopes.A voice coil adaptive deformable mirror contains a large number of actuators,and there are problems with structural coupling and large temperature increases in their internal coils.Additionally,parameters of the traditional proportional integral derivative(PID)control cannot be adjusted in real-time to adapt to system changes.These problems can be addressed by introducing fuzzy control methods.A table lookup method is adopted to replace real-time calculations of the regular fuzzy controller during the control process,and a prototype platform has been established to verify the effectiveness and robustness of this process.Experimental tests compare the control performance of traditional and fuzzy proportional integral derivative(Fuzzy-PID)controllers,showing that,in system step response tests,the fuzzy control system reduces rise time by 20.25%,decreases overshoot by 78.24%,and shortens settling time by 67.59%.In disturbance rejection experiments,fuzzy control achieves a 46.09%reduction in the maximum deviation,indicating stronger robustness.The Fuzzy-PID controller,based on table lookup,outperforms the standard controller significantly,showing excellent potential for enhancing the dynamic performance and disturbance rejection capability of the voice coil motor actuator system.

Prototypes,modifications,and hydrocarbon enrichment variations in basins influenced by Tethyan evolution:A comparative analysis of the Persian Gulf Basin and the Sichuan Basin

The hydrocarbon accumulation modes and differences in the Tethyan realm serve as a hot research topic in the petroleum geology community at home and abroad.Both the Persian Gulf Basin in the Middle East and the Sichuan Basin in China,situated on the southern and northern sides of the Tethyan realm,respectively,record the whole geological process of the opening and closure of the Prototethys,the Paleotethys,and the Neotethys sequentially,exhibiting anomalous hydrocarbon enrichment.Based on the analysis of the plate tectonic evolution in the Tethyan realm,this study dissects the structures and hydrocarbon accumulation conditions of both basins.Followed by a systematic comparative analysis of the factors controlling hydrocarbon enrichment in the process of plate breakup and convergence in the Tethyan realm,this study proposes petroleum exploration targets in the realm.The results are as follows:(1)Since the Meso-Neoproterozoic,the Persian Gulf Basin and the Sichuan Basin have undergone similar tectonic evolution in the early stage but different in the late stage.Under the influence of the formation and evolution of the Prototethys,Paleotethys,and Neotethys oceans,both basins experienced multi-stage development and modification,forming two major extension-convergence cycles.Consequently,both basins are characterized by the vertical orderly superimposition of various basin prototypes in the order of rift-intracratonic basin(passive continental margin)-foreland.(2)The fact that the Tethyan realm was long located at medium-low latitudes and the local anoxic environment formed in the process of plate breakup and convergence played a vital role in the formation of extensive source rocks.The source rocks are predominantly distributed in underfilled rifts and deep depressions that were connected to the ocean in the unidirectional continental breakup process;basin-slopes and intra-shelf basins on passive continental margins;basinal lows within intracratonic basins,and underfilled foredeeps in foreland basins.The favorable areas for the formation of carbonate reservoirs include platform margins,submarine highs and paleo-uplifts within platforms,and fault zones.The evaporite cap rocks,intimately associated with the basin evolutionary stages and global dry-hot events,are critical for large-scale hydrocarbon preservation.(3)Under the influence of Tethyan evolution,the Persian Gulf Basin and the Sichuan Basin share similar primary factors controlling hydrocarbon enrichment.The moderate tectono-sedimentary differentiation and structural modification in the process of prototype basin superimposition,as well as the spatio-temporal matching of elements critical for hydrocarbon accumulation,are beneficial for the development of large oil and gas fields.The macroscopic hydrocarbon distribution is dictated by source rock-cap rock assemblages,while the local hydrocarbon distribution is governed by trap-reservoir assemblages.The critical factors determining the differential hydrocarbon enrichment in the Persian Gulf Basin and the Sichuan Basin include plate size and position,basement stability,eustatic movement,paleoclimate,and tectonic transformation.Besides,different tectonic modification intensities are closely related to the type,enrichment degree,and distribution of hydrocarbon reservoirs.

Selective photo-reduction of nitrate to nitrogen with a two-step process by a KBH_(4)/Cu(II)modified CuFe_(2)O_(4)photocatalyst

Nitrate(NO_(3)^(-))removal by photochemical-reduction has received extensive attention.However,the low selectivity of NO_(3)^(-)reduction to N_(2)hinders the application of this technology.In this study,a novel Cu@Fe-Cu-CuFe_(2)O_(4)-x photocatalyst was prepared by modifying CuFe_(2)O_(4)with KBH4 and Cu(II),and used to selectively reduce NO_(3)^(-)to N_(2)with a two-step reduction process.In step(1),with Cu@Fe-Cu-CuFe_(2)O_(4)-x/ultraviolet(UV)system,91.0%NO_(3)^(-)was reduced to 52.3%NO_(2)-and 39.4%N_(2)within 60 min.The rapid removal of NO_(3)^(-)was due to the synergistic effect of oxygen vacancies,Fe-Cu corrosion cell,and CuFe_(2)O_(4)photocatalysis.In step(2),H_(2)C_(2)O_(4)and H_(2)O_(2)were introduced into the effluent of step(1)to promote CO_(2)·-formation via Fe(II)and Fe(III)catalysis and UV radiation,which boosted the selective reduction of NO_(2)-to N_(2).When H_(2)C_(2)O_(4)and H_(2)O_(2)dosages were both 4.0 mmol·L^(-1)and the reaction time was 30 min,the removal efficiency of NO_(2)-achieved 100%and the selectivity of N_(2)was 83.0%.Overall,the two-step reduction process achieved 95.0%NO_(3)^(-)removal efficiency and 90.1%N_(2)selectivity with initial NO_(3)^(-)concentration of 30 mg·N·L^(-1).In addition,the denitrification mechanism of the two-step reduction process was tentatively proposed.

Hydrocarbon migration in fracture-cave systems of carbonate reservoirs under tectonic stresses:A modeling study

The Tahe oilfield,located in the southwest of the Akekule nosing structure,northern Tarim basin,was the most prolific oilfield targeting at the Ordovician carbonate reservoirs in China.The reservoir space was dominant with fracture-cave systems commonly induced by tectonics and karstification.Although hydrocarbon production had proceeded for two decades in the Tahe oilfiled,the control of oil and gas accumulations was still doubtful.In this work,the periodic fluid flow induced by cyclic tectonic stresses was proposed as the mechanism of hydrocarbon migration in the fracture-cave systems of carbonate reservoirs.The fracture networks formed conduits for fluid flow,and the fluid pressure in caves transmitted from stress field provided the driving force.The constitutive equations were established among stresses,fracture densities and flow velocities.Four quasi-3D geological models were constructed to simulate the flow velocities on the Ordovician surface of Akekule nosing structure in the critical tectonic stages.The simulated results supplied indicative information on oil and gas migration and accumulation in the tectonic stages.Combining with the oil and gas charge history,a conceptual model was built to reveal the multi-stage oil and gas charge and accumulation in the Ordovician of Akekule nosing structure.

Hydrocarbon migration in fracture-cave systems of carbonate reservoirs under tectonic stresses: A mechanism study

The fracture-cave systems of carbonate reservoirs have almost stored 30% of recoverable oil and gasaround the world. However, it is still doubtful about the mechanism of hydrocarbon migration in thefracture-cave systems. In this work, deducing from the Eshelby’ solution, we derived the equation tocalculate the bulk strain of elliptic cylinder caves applied by stresses. Calculated results indicate that thebulk strain of caves negatively increases with the radius ratio of the elliptic cave axials under fixedstresses. In the case of the effective horizontal stress increasing from 30 MPa to 80 MPa, the bulk straindifference of a cave could be up to 0.5%. It may result in 0.4% of the total cave volume of fluid transportingthrough the fracture-cave systems within such a stress cycle. Since the tectonic stresses transform in acyclic way, the volumetric ratio of new-to-old fluid in a cave would increase with the number of stresscycles. As a result, we proposed that the periodic fluid flow induced by cyclic tectonic stresses could be animportant mechanism for hydrocarbon migration in the fracture-cave systems of carbonate reservoirs.

High-temperature ferromagnetic metallic phase in LaMnO_(3)/Sr_(3)Al_(2)O_(6)heterostructure

To achieve a flexible single-crystal multifunctional membrane,the freestanding process of a rigid epitaxial transition metal oxide thin film via a buffered water-dissolution sacrificial layer has attracted reasonable attentions.Owing to the difference in chemical potential,specific element affinity,and lattice constant between the target membrane and the sacrificial layer,the freestanding process may cause an indelible change of physics property once the target thin film is sensitive to the above factors.Here,the heterostructures composed of the generally adopted sacrificial layer Sr_(3)Al_(2)O_(6)(SAO)and LaMnO_(3)(LMO)have been systematically investigated.The electrical and magnetic properties of LMO show extreme sensitivity to the thickness of SAO(tSAO).Then we have also found that LMO/SAO heterostructures can exhibit the coexistence of two ferromagnetic phases,the significantly enhanced Curie temperature~342 K,and the large magnetoresistance-23.3%at 300 K,which is similar to the optimal-doped manganite such as La_(2/3)Sr_(1/3)MnO_(3).X-ray diffraction results show that continuously tunable strain from out-of-plane tension to relaxation and then to compression can be generated by adjusting tSAO.This strain can stabilize the migrated oxygen from LMO to SAO,which is induced by the large oxygen affinity difference between Bsite Mn and Al.It is believed that these unexpected electrical/magnetic phenomena are originated from the combined effects of interfacial element diffusion and strain.Our study provides a strategy for designing new magnetic phases,and a reference for the fundamental understanding of strongly correlated transition metal oxide systems in the freestanding process.