Localized surface plasmon polaritons, which are referred to simply as localized surface plasmons, are carrier oscillations in inorganic nanoparticles (NPs) that are excited by incident light waves. At the NP surface, the localized surface plasmons exhibit enhanced near-field amplitudes, which are highly localized at the NP surface and decay rapidly in the dielectric surroundings. A very important aspect of localized surface plasmons is the localization of an enhanced electromagnetic field around the NPs with very high spatial resolution (subwavelength). A precise control over the free electron density of indium tin oxide NPs enables us to tune the LSPR wavelength in the NIR regions. An electric field enhancement based on NIR surface plasmons was estimated to be 5.24-4.41. The surface plasmon coupling between highly symmetrical Au dimers was investigated in detail, and a dark plasmon coupling mode was found to be applied to the plasmon propagation without significant scattering loss.
The roles of electrons and holes in photo-excited samarium doped titanium dioxide (TiO2:Sm) thin film were investigated with electric measurement techniques. For this purpose, a structural modification using interface states in silicon oxide between TiO2:Sm and a conductive silicon substrate was used. Since the interface states make a barrier to electrons in positive DC bias VDC, selective injection of holes into TiO2:Sm can be realized in VDC>0. Photo-excited dielectric relaxation (PEDR) technique, namely frequency dispersion measurement of complex impedance under excitation light, and the selective injection revealed that the Sm excitation was induced by an electron trapping with a slow response of ∼12 Hz and following recombination with holes in host TiO2 with ∼950 Hz.
A p-GaN semiconductor is the more suitable photocathode material than a p-GaAs semiconductor, because a p-type semiconductor with wide band gap has large vacuum level shift caused by surface band bending. We measured quantum yield degradation and quantum yield spectrum of a p-GaN photocathode with an NEA surface. The p-GaN photocathode had the process of quantum yield degradation from the extraction of photocurrent and the residual gas, it is found to be important to suppress backs-pattering due to the increase of background pressure. From the dependence of quantum yield of the p-GaN photocathode on excitation wavelength, the quantum yield spectrum rapidly increased around the band gap of GaN as expected.
A numerical analysis by solving the time-dependent Schrödinger equation on a neon atom within the single-active electron approximation shows that a two-color laser field synthesized from a sub-12-fs fundamental field and a detuned second harmonic field with a wavelength shorter than 380nm is suitable for generating an intense isolated attosecond pulse (IAP). We have also investigated the effects of carrier-envelope phase variation on the obtained IAP and have compared the results to those obtained from a 5-fs fundamental field alone with the same peak field amplitude to show that a more intense IAP can be generated by the two-color laser field which is useful for nonlinear experiments in the extreme ultraviolet spectral range.
Recently, external enhancement cavities have been employed for the improvement of the conversion efficiency in various wavelength conversions. Indeed, the external enhancement cavities are very attractive because they are constructed without any sophisticated optical configuration and therefore we have expected that they are so applicable in the enhancement of the fundamental lights as to be utilized with a variety of light sources. In this study, we demonstrated the second harmonic generations (SHGs) of both an infrared continuous wave (CW) light and a mode-locked picosecond pulsed light in a similar external enhancement cavity with the same BiB3O6 (BiBO). Then we confirmed the enhancement effects for both lights. The maximum output power of the CW second harmonic light was 430mW and then the conversion efficiency was 54%. On the other hand, the maximum output power of the picosecond pulsed second harmonic light was 560mW and then the conversion efficiency was 70%. These values are excellent results in SHG with BiBO crystal in spite of the relatively low fundamental power. From the SHG output characteristics, we performed comparison of the optimization conditions of both external enhancement cavities and the characteristics of the enhancement effects.
We propose a method to optimize two-color laser fields, composed of an intense driving pulse at 580 nm and a weaker control pulse at 1160 nm, for isolated attosecond pulse generation. We use genetic algorithm (GA) to optimize laser parameters including the group-delay dispersion and the third-order dispersion of the control pulse. The fitness function is constructed by directly using the duration of the generated high-harmonic extreme ultraviolet (XUV) pulse. Our simulation results show that the isolated attosecond pulse can be significantly shortened without much affecting its spectral width.
We observed that the emission intensity in extreme and vacuum ultraviolet spectral regions using a laser-produced copper tungsten alloy plasma was 1.3 times higher than that using a pure tungsten plasma. The enhancement of the emission intensity was explained by the difference of the Rosseland mean opacity of each plasma.
Photo-acoustics has been widely studied as new imaging modalities, which combines the merits of optical and acoustical methods. This imaging technology has the potential with high contrast and high spatial resolution. The state-of-the-art photo-acoustic imaging technology and our original approach to the functional image will be introduced.
Change in electronic states before and after photo-irradiation at a Donor/Accepter (D/A) interface in organic solar cells consisting of Zinc-porphyrin and fullerene films has been examined using in situ impedance spectroscopy (IS), which makes it possible to non-destructively measure a built-in potential (Vbi) of both D and A films at the D/A interface. Charge accumulation of photo-generated carriers in the vicinity of the D/A interface was found to enlarge the Vbi of both D [Zn(OEP)] and A [C60] films at the interface. In addition, it was noted that the sum of Vbi upon photo-irradiation was in good agreement with the open-circuit voltage (VOC), the origin of which has still remained unsolved for organic solar cells. It was thus found that charge accumulation of photo-generated carriers in the vicinity of the D/A interface plays a key role in determining VOC.
Time-dependent restricted and unrestricted Hartree-Fock (TD-RHF and TD-UHF) methods are comparatively assessed for the description of the electron dynamics in intense laser fields. These methods are applied to the one-dimensional H2 molecule exposed to an intense laser field, and compared to the results from the time-dependent Schrödinger (TDSE) equation. Around the equilibrium interatomic distance, where the initial RHF and UHF wavefunctions coincide, TD-UHF keeps an initial closed-shell, thus underestimates large amplitude electron motions. At a longer interatomic distance, where the UHF wavefunction differs from the RHF one, TD-UHF better reprodeces the TDSE result than TD-RHF does.
We experimentally investigated the wavelength tuning of oscillating idler (Stokes) waves by slightly translating the position of a mirror constituting an enhancement cavity in a terahertz (THz)-wave parametric oscillator (TPO) with optical double resonance. The wide tuning range of the idler wavelength was from 781.5 to 787.3 nm, corresponding to the frequency range of THz (signal) waves from 0.7 to 3.5 THz. The measured intersecting angle between pump and idler waves was in good agreement with the theoretical calculation of the noncollinear phase-matching condition in all the above tuning range.
A wireless power transfer system that is made of magnetically coupled resonators is designed for 0Ω power source. The design is based on the BPF theory, which insists more restrictive condition than the conventional power factor condition. But it gives wider operating bandwidth and higher power transfer efficiency. The present paper derives the condition analytically and shows some useful design examples, including 2-stage as wall as 3-stage system, and a system with a loop coil to transform the load impedance.
A multi-layer composite right/left-handed (M-CRLH) transmission line (TL) was firstly proposed in 2004 as a new architecture to realize super-compact left-handed metamaterials, and the latest LTCC-based M-CRLH TL, with dimensions of 1.5mm×1.5mm×0.95mm, has a wide, flat, and low-insertion-loss passband with a fractional bandwidth of more than 130%. However, it still suffers from a deep transmission zero (TZ) yielded in a right-handed frequency region. This paper develops a new equivalent circuit model based on electromagnetic field simulations and explains creation mechanism of the TZ successfully by considering an inner-coupling in the unit-cell. Based on this argument, an ultra wideband TZ-free M-CRLH is designed and demonstrated.
This paper conducted experiments to model the channel for digital transmission based on the analysis of the experimental results obtained, and revealed the characteristics of propagation loss, characteristics of delay path profile and the noise characteristics of the power line carrier system that uses power transmission lines. In terms of the characteristics of propagation loss, experimental results were subjected to multiple regression analysis and an equation to estimate propagation loss was derived with useful parameters. With the characteristics of delay path profile, additional loss of the delay path was modeled and clarified. It was indicated that delay path travel both by in-phase propagation and out-phase propagation, thus it is important to consider these two propagation characteristics when modeling. With the noise characteristics, it was indicated that they are superposition characteristics of thermal noise and impulse noise and these two characteristics were modeled based on theoretical examination and the cumulative probability distribution. Simulations using these derived models agreed well with the measurement results, indicating these models will be practical for use.
It is known that the SSCF (Square Sum of Correlation Function) adaptive algorithm is robust for the sound noise added at the input. In this paper we propose an active noise control system using SSCF adaptive algorithm. The comparison of the required degree of the adaptive filter to the conventional system using the filterd-x adaptive algorithm is presented. The analysis and the numerical verifications of the convergence performance of this system are also presented.
The adaptive notch filter that is composed of the exponential type all-pass circuit has the stable and the robust characteristics for the broadband signal. In this paper, we propose a method to reduce the number of the adaptive parameters and adaptive algorithm using the frequency sampling adaptive filter with reduction of the phase shift samples. It was shown that the reduction of one digit or more was possible by the use of the property of the notch filter with small bandwidth.
Many researches and developments of table-top interface have been proposed in the last decade. In a table-top system, the difference of operations between the digital media and the physical media like a paper gives us unsatisfactory experience and disturbs a comfortable simultaneous using of them. It is required for user satisfaction that the user can operate the digital and physical media seamlessly. In this paper, we propose a table-top interface system that allows users to operate digital media intuitively by using gesture recognition. The proposed table can capture an image of the object on the table by press gesture recognition from users' nail images based on SVM, and can acquire a digital content from a digital paper reader by shake gesture of the device. The evaluation experiments show that the proposed system recognizes users' finger state with higher accuracy and the users can intuitively operate the table without awareness of the data transmission.
The Internet news are texts which involve from various fields, therefore, when a text data that will show a rapid increase of the number of dimensions of feature vectors of Self-Organizing Map (SOM) is added, these results cannot be reflected to learning. Furthermore, it is difficult for users to recognize the learning results because SOM can not produce any label information by each cluster. In order to solve these problems, we propose SOM with additional learning and dimensional by category mapping which is based on the category structure of Wikipedia. In this method, input vector is generated from each text and the corresponding Wikipedia categories extracted from Wikipedia articles. Input vectors are formed in the common category taking the hierarchical structure of Wikipedia category into consideration. By using the proposed method, the problem of reconfiguration of vector elements caused by dynamic changes in the text can be solved. Moreover, information loss in newly obtained index term can be prevented.
Differential Evolution (DE) is an effective optimization method for global continuous optimization problems. Recently, we developed Local Descent Direction Vector Based Differential Evolution (LDDVDE) which uses local descent direction vectors based on the operation vectors in order to improve local search performance of DE. In this paper, we extend LDDVDE to multiobjective optimization problems. We adopt Hyper-Volume indicator to order the operation vectors to make the local descent direction vectors for the case of multiobjective optimization problems. The effectiveness of the proposed method is confirmed through some numerical experiments for typical benchmark problems.
Weblogs have greatly changed the communication ways of mankind. Affective analysis of blog posts is found valuable for many applications such as text-to-speech synthesis or computer-assisted recommendation. Traditional emotion recognition in text based on single-label classification can not satisfy higher requirements of affective computing. In this paper, the automatic identification of sentence emotion in weblogs is modeled as a multi-label text categorization task. Experiments are carried out on 12273 blog sentences from the Chinese emotion corpus Ren_CECps with 8-dimension emotion annotation. An ensemble algorithm RAKEL is used to recognize dominant emotions from the writer's perspective. Our emotion feature using detailed intensity representation for word emotions outperforms the other main features such as the word frequency feature and the traditional lexicon-based feature. In order to deal with relatively complex sentences, we integrate grammatical characteristics of punctuations, disjunctive connectives, modification relations and negation into features. It achieves 13.51% and 12.49% increases for Micro-averaged F1 and Macro-averaged F1 respectively compared to the traditional lexicon-based feature. Result shows that multiple-dimension emotion representation with grammatical features can efficiently classify sentence emotion in a multi-label problem.
Under the anticipated high penetration of variable renewable energy generation such as photovoltaics and higher share of nuclear generation, the issue of supply-demand balancing capability should be evaluated and fixed in a future power system. Improvement of existing balancing measures and new technologies such as demand activation and energy storage are expected to solve the issue. Under the situation, a long-range power system supply-demand analysis should have the capability to evaluate the balancing capability and balancing counter measures. This paper presents a new analysis methodology of activated demand model and evaluation of supply-demand balancing capability for a long-range power system demand-supply analysis model, ESPRIT. Model analysis was made to verify the new methodology of the tool including day-ahead scheduling of a heat pump water heater, an EV/PHEV and a battery.
A continuous-time plant with discretized continuous-time controller do not yield stability if the sampling rate is lower than some certain level. Thus far, high functioning electronic control has made use of high cost hardwares which are needed to implement discretized continuous-time controllers, while low cost hardwares generally do not have high enough sampling rate. This technical note presents results comparing performance indices with and without intersample behavior, and some answer to the question how a low specification device can control a plant effectively. We consider a machine simulating wafer handling robots at semiconductor factories, which is an electromechanical system driven by a direct drive motor. We illustrate controller design for the robot with and without intersample behavior, and simulations and experimental results by using these controllers. Taking intersample behavior into account proves to be effective to make control performance better and enables it to choose relatively long sampling period. By controller design via performance index with intersample behavior, we can cope with situation where short enough sampling period may not be employed, and freedom of controller design might be widened especially on choice of sampling period.
Some assessments have been applied to find possible factors that might lead to child abuse. PACAP is a new method proposed by Ueda and others as a pre-assessment of the concerning child abuse, which reduces its false-positive misclassification. The Internet PACAP is developed to reduce the laborious work of nurses and health care workers for the necessary processing and classifying the scores of the pre-assessment. The present system is expected to prevent the child abuse more effectively.