AIM: To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles.METHODS: Sixty ametropia juveniles(aged range,11-15y) were randomized into two group...AIM: To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles.METHODS: Sixty ametropia juveniles(aged range,11-15y) were randomized into two groups: the test group(30 children,60 eyes),wearing blue-violet light filtering lenses; and the control group(30 children,60 eyes),wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year,the patients underwent contrast sensitivity(glare and non-glare under bright and dark conditions),accommodation-related testing,asthenopia questionnaire assessment,and adverse reaction questionnaire assessment. RESULTS: After 1y of wearing the filtering lenses,changes in refractive power and axial length were not significantly different between the two groups(P>0.05). Under bright conditions,the contrast sensitivities at low and mediumfrequency grating(vision angles of 6.3°,4.0°,and 2.5°) with glare in the test group were significantly higher than in the control group(P<0.05),while the contrast sensitivity at low-frequency grating(vision angles of 6.3° and 4.0°) in the absence of glare in the test group was higher than in the control group(P<0.05). Under glare and non-glare dark conditions,the contrast sensitivities of various frequencies in the test group did not show significant differences compared with those in the control group(P>0.05). In the test group,the amplitude of accommodation,accommodative lag,and accommodative sensitivity of patients wearing glasses for 6 and 12 mo were significantly elevated(P<0.05),while the asthenopia gratings were significantly decreased(P<0.05). Nevertheless,in the control group,the amplitude of accommodation,accommodative lag,and accommodative sensitivity after 12 mo were not significantly altered compared with baseline(P>0.05),and the asthenopia grating was not significantly decreased(P>0.05). In addition,after wearing glasses for 6 to 12 mo,the asthenopia grating of patients in the test group decreased significantly compared with the control group(P<0.05). At 12 mo,the constituent ratio of adverse reactions did not show significant difference between the two groups(P>0.05). CONCLUSION: A1-year follow-up reveal that compare with ordinary glasses,short-wavelength filtering lenses(blue/violet-light filters) increase the low-and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions,suggesting potential for clinical application. However,no significant advantages in terms of refractive power or axial length progression were found compared with ordinary aspheric lenses.展开更多
A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is ob...A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n<sup><span style="font-family:Verdana;">+</span></sup><span style="font-family:Verdana;">/p) and the rear face (p/p</span><sup><span style="font-family:Verdana;">+</span></sup><span style="font-family:Verdana;">) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">modulated frequency of back illumination. Thus under these operating conditions</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> a maximum short-circuit photocurrent is obtained and a low</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.</span>展开更多
In this paper,we demonstrate bias-selectable dual-band short-or mid-wavelength infrared photodetectors based on In_(0.24)Ga_(0.76)As_(0.21)Sb_(0.79)bulk materials and InAs/GaSb type-II superlattices with cutoff wavele...In this paper,we demonstrate bias-selectable dual-band short-or mid-wavelength infrared photodetectors based on In_(0.24)Ga_(0.76)As_(0.21)Sb_(0.79)bulk materials and InAs/GaSb type-II superlattices with cutoff wavelengths of 2.2μm and 3.6μm,respectively.At 200 K,the short-wave channel exhibits a peak quantum efficiency of 42%and a dark current density of5.93×10^(-5)A/cm^2at 500 mV,thereby providing a detectivity of 1.55×10^(11)cm·Hz^(1/2)/W.The mid-wave channel exhibits a peak quantum efficiency of 31%and a dark current density of 1.22×10^(-3)A/cm^2at-300 mV,thereby resulting in a detectivity of 2.71×10^(10)cm·Hz^(1/2)/W.Moreover,we discuss the band alignment and spectral cross-talk of the dual-band n-i-p-p-i-n structure.展开更多
Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the constructi...Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the construction and operation of HWACT to analyze its fault features and corresponding protection technology. In this paper, the steady-state voltage and current characteristics of the bus bar and fault point and the steady-state overvoltage distribution along the line will be analyzed when a three-phase symmetrical short-circuit fault occurs on an HWACT line. On this basis, the threephase fault characteristics for longer transmission lines are also studied.展开更多
基金Supported by Projects of Medical and Health Technology Development Program in Zhejiang Province(No.2011KYA020)
文摘AIM: To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles.METHODS: Sixty ametropia juveniles(aged range,11-15y) were randomized into two groups: the test group(30 children,60 eyes),wearing blue-violet light filtering lenses; and the control group(30 children,60 eyes),wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year,the patients underwent contrast sensitivity(glare and non-glare under bright and dark conditions),accommodation-related testing,asthenopia questionnaire assessment,and adverse reaction questionnaire assessment. RESULTS: After 1y of wearing the filtering lenses,changes in refractive power and axial length were not significantly different between the two groups(P>0.05). Under bright conditions,the contrast sensitivities at low and mediumfrequency grating(vision angles of 6.3°,4.0°,and 2.5°) with glare in the test group were significantly higher than in the control group(P<0.05),while the contrast sensitivity at low-frequency grating(vision angles of 6.3° and 4.0°) in the absence of glare in the test group was higher than in the control group(P<0.05). Under glare and non-glare dark conditions,the contrast sensitivities of various frequencies in the test group did not show significant differences compared with those in the control group(P>0.05). In the test group,the amplitude of accommodation,accommodative lag,and accommodative sensitivity of patients wearing glasses for 6 and 12 mo were significantly elevated(P<0.05),while the asthenopia gratings were significantly decreased(P<0.05). Nevertheless,in the control group,the amplitude of accommodation,accommodative lag,and accommodative sensitivity after 12 mo were not significantly altered compared with baseline(P>0.05),and the asthenopia grating was not significantly decreased(P>0.05). In addition,after wearing glasses for 6 to 12 mo,the asthenopia grating of patients in the test group decreased significantly compared with the control group(P<0.05). At 12 mo,the constituent ratio of adverse reactions did not show significant difference between the two groups(P>0.05). CONCLUSION: A1-year follow-up reveal that compare with ordinary glasses,short-wavelength filtering lenses(blue/violet-light filters) increase the low-and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions,suggesting potential for clinical application. However,no significant advantages in terms of refractive power or axial length progression were found compared with ordinary aspheric lenses.
文摘A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n<sup><span style="font-family:Verdana;">+</span></sup><span style="font-family:Verdana;">/p) and the rear face (p/p</span><sup><span style="font-family:Verdana;">+</span></sup><span style="font-family:Verdana;">) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">modulated frequency of back illumination. Thus under these operating conditions</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> a maximum short-circuit photocurrent is obtained and a low</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.</span>
基金Project supported by the National Basic Research Program of China(Grant Nos.2016YFB0402403 and 2013CB932904)the National Natural Science Foundation of China(Grant Nos.61290303 and 61306013)China Postdoctoral Science Foundation(Grant No.2016M601100)
文摘In this paper,we demonstrate bias-selectable dual-band short-or mid-wavelength infrared photodetectors based on In_(0.24)Ga_(0.76)As_(0.21)Sb_(0.79)bulk materials and InAs/GaSb type-II superlattices with cutoff wavelengths of 2.2μm and 3.6μm,respectively.At 200 K,the short-wave channel exhibits a peak quantum efficiency of 42%and a dark current density of5.93×10^(-5)A/cm^2at 500 mV,thereby providing a detectivity of 1.55×10^(11)cm·Hz^(1/2)/W.The mid-wave channel exhibits a peak quantum efficiency of 31%and a dark current density of 1.22×10^(-3)A/cm^2at-300 mV,thereby resulting in a detectivity of 2.71×10^(10)cm·Hz^(1/2)/W.Moreover,we discuss the band alignment and spectral cross-talk of the dual-band n-i-p-p-i-n structure.
基金supported by National Key Research and Development Program of China(2016YFB0900100)
文摘Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the construction and operation of HWACT to analyze its fault features and corresponding protection technology. In this paper, the steady-state voltage and current characteristics of the bus bar and fault point and the steady-state overvoltage distribution along the line will be analyzed when a three-phase symmetrical short-circuit fault occurs on an HWACT line. On this basis, the threephase fault characteristics for longer transmission lines are also studied.
