Browsing by Issue Date, starting with "2014-08-22"

Now showing 1 - 20 of 25761

A clustering time series model for the optimal hedge ratio decision making
(2014-08-22)
Hsu, Yu-Chia
;
Chen, An-Pin
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
In this study, a novel procedure combining computational intelligence and statistical methodologies is proposed to improve the accuracy of minimum-variance optimal hedge ratio (OHR) estimation over various hedging horizons. The time series of financial asset returns are clustered hierarchically using a growing hierarchical self-organizing map (GHSOM) based on the dynamic behaviors of market fluctuation extracted by measurement of variances, covariance, price spread, and their first and second differences. Instead of using original observations, observations with similar patterns in the same cluster and weighted by a resample process are collected to estimate the OHR. Four stock market indexes and related futures contracts, including Taiwan Weighted Index (TWI), Standard & Poor\'s 500 Index (S&P 500), Financial Times Stock Exchange 100 Index (FUSE 100), and NIKKEI 255 Index, are adopted in empirical experiments to investigate the correlation between hedging horizon and performance. Results of the experiments demonstrate that the proposed approach can significantly improve OHR decisions for mid-term and long-term hedging compared with traditional ordinary least squares and naive models. (C) 2014 Elsevier B.V. All rights reserved.
Quantum critical point in the superconducting transition on the surface of a topological insulator
(2014-08-25)
Li, Dingping
;
Rosenstein, Baruch
;
Shapiro, B. Ya
;
Shapiro, I.
;
電子物理學系
Pairing in the Weyl semimetal appearing on the surface of a topological insulator is considered. It is shown that due to an "ultrarelativistic" dispersion relation there is a quantum critical point governing the zero-temperature transition to a superconducting state. Starting from the microscopic Hamiltonian with local attraction, we calculated using the Gor'kov equations, the phase diagram of the superconducting transition at arbitrary chemical potential, and its magnetic properties and critical exponents close to the quantum critical point. The Ginzburg-Landau (GL) effective theory is derived for small chemical potential, allowing us to consider effects of spatial dependence of order parameters in a magnetic field. The GL equations are very different from the conventional ones reflecting the chiral universality class of the quantum phase transition. The order-parameter distribution of a single vortex is found to be different as well. The magnetization near the upper critical field is found to be quadratic, not linear as usual. We discuss the application of these results to recent experiments in which surface superconductivity was found for some three-dimensional topological insulators, and we estimate feasibility of the phonon pairing.
Fabrication and characterization of back-side illuminated InGaN/GaN solar cells with periodic via-holes etching and Bragg mirror processes
(2014-08-25)
Chang, Yi-An
;
Chen, Fang-Ming
;
Tsai, Yu-Lin
;
Chang, Ching-Wen
;
Chen, Kuo-Ju
In this study, the design and fabrication schemes of back-side illuminated InGaN/GaN solar cells with periodic via-holes etching and Bragg mirror processes are presented. Compared to typical front-side illuminated solar cells, the improvements of open-circuit voltage (V-oc) from 1.88 to 1.94 V and short-circuit current density (J(sc)) from 0.84 to 1.02 mA/cm(2) are observed. Most significantly, the back-side illuminated InGaN/GaN solar cells exhibit an extremely high fill factor up to 85.5%, leading to a conversion efficiency of 1.69% from 0.66% of typical front-side illuminated solar cells under air mass 1.5 global illuminations. Moreover, the effects of bottom Bragg mirrors on the photovoltaic characteristics of back-side illuminated solar cells are studied by an advanced simulation program. The results show that the J(sc) could further be improved with a factor of 10% from the original back-side illuminated solar cell by the structure optimization of bottom Bragg mirrors. (C) 2014 Optical Society of America
Spatial and electrical switching of defect modes in a photonic bandgap device with a polymer-dispersed liquid crystal defect layer
(2014-08-25)
Wu, Po-Chang
;
Yeh, En-Rong
;
Zyryanov, Victor Ya.
;
Lee, Wei
;
影像與生醫光電研究所
This paper investigates the spectral properties of a one-dimensional photonic crystal (PC) containing an inhomogeneous polymer-dispersed liquid crystal (PDLC) as a defect layer. Experimental results indicate that the voltage-induced reorientation of LC molecules between the light-scattering and transparent states in the PDLC enables the electrical tuning of the transmittance of defect-mode peaks in the spectrum of the PC/PDLC cell. Specifically, owing to the unique configuration of the spatial distribution of LC droplet sizes in the defect layer, a concept concerning the spatial switching in the wavelength of defect modes is proposed. As a result, the PC/PDLC hybrid cell is suggested as a potential element for realizing an electrically tunable and spatially switchable photonic bandgap device, which is polarizer-free and requires no alignment layers in the fabrication process. (C) 2014 Optical Society of America
Femtosecond Excitonic Relaxation Dynamics of Perovskite on Mesoporous Films of Al2O3 and NiO Nanoparticles
(2014-08-25)
Hsu, Hung-Yu
;
Wang, Chi-Yung
;
Fathi, Amir
;
Shiu, Jia-Wei
;
Chung, Chih-Chun
The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up-conversion. The temporal profiles of emission observed in spectral region 670-810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time-amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the non-emissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al2O3 film. We conclude that perovskite is an effective hole carrier in a p-type electrode for NiO-based perovskite solar cells showing great performance.
Is blue optical filter necessary in high speed phosphor-based white light LED visible light communications?
(2014-08-25)
Sung, Jiun-Yu
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
光電工程學系
;
Department of Photonics
Optical blue filter is usually regarded as a critical optical component for high speed phosphor-based white light emitting diode (LED) visible-light-communication (VLC). However, the optical blue filter plays different roles in VLC when using modulations of on-off keying (OOK) or discrete multi-tone (DMT). We show that in the DMT VLC system, the blue optical filter may be unnecessary, and even degrade the transmission performance (by reducing the optical signal-to-noise ratio (SNR)). Analyses and verifications by experiments are performed. To the best of our knowledge, this is the first time the function of blue filters in VLC is explicitly analyzed. (C) 2014 Optical Society of America
Negative correlation between charge carrier density and mobility fluctuations in graphene
(2014-08-26)
Lu, Jianming
;
Pan, Jie
;
Yeh, Sheng-Shiuan
;
Zhang, Haijing
;
Zheng, Yuan
By carrying out simultaneous longitudinal and Hall measurements in graphene, we find that the 1/f noise for the charge carrier density is negatively correlated to that of mobility, with a governing behavior that differs significantly from the relation between their mean values. The correlation in the noise data can be quantitatively explained by a single-parameter theory whose underlying physics is the trapping and detrapping of the fluctuating charge carriers by the oppositely charged Coulomb scattering centers. This can alter the effective density of long-range scattering centers in a transient manner, with the consequent fluctuating effect on the mobility.
Electronic conduction properties of indium tin oxide: single-particle and many-body transport
(2014-08-27)
Lin, Juhn-Jong
;
Li, Zhi-Qing
;
電子物理學系
;
Department of Electrophysics
Indium tin oxide (Sn-doped In2O3-delta or ITO) is a very interesting and technologically important transparent conducting oxide. This class of material has been extensively investigated for decades, with research efforts mostly focusing on the application aspects. The fundamental issues of the electronic conduction properties of ITO from room temperature down to liquid-helium temperatures have rarely been addressed thus far. Studies of the electrical-transport properties over a wide range of temperature are essential to unravelling the underlying electronic dynamics and microscopic electronic parameters. In this topical review, we show that one can learn rich physics in ITO material, including the semi-classical Boltzmann transport, the quantum-interference electron transport, as well as the many-body Coulomb electron-electron interaction effects in the presence of disorder and inhomogeneity (granularity). To fully reveal the numerous avenues and unique opportunities that the ITO material has provided for fundamental condensed matter physics research, we demonstrate a variety of charge transport properties in different forms of ITO structures, including homogeneous polycrystalline thin and thick films, homogeneous single-crystalline nanowires and inhomogeneous ultrathin films. In this manner, we not only address new physics phenomena that can arise in ITO but also illustrate the versatility of the stable ITO material forms for potential technological applications. We emphasize that, microscopically, the novel and rich electronic conduction properties of ITO originate from the inherited robust free-electron-like energy bandstructure and low-carrier concentration (as compared with that in typical metals) characteristics of this class of material. Furthermore, a low carrier concentration leads to slow electron-phonon relaxation, which in turn causes the experimentally observed (i) a small residual resistance ratio, (ii) a linear electron diffusion thermoelectric power in a wide temperature range 1-300 K and (iii) a weak electron dephasing rate. We focus our discussion on the metallic-like ITO material.
Scale Effect on Dropwise Condensation on Superhydrophobic Surfaces
(2014-08-27)
Lo, Ching-Wen
;
Wang, Chi-Chuan
;
Lu, Ming-Chang
;
機械工程學系
;
Department of Mechanical Engineering
Micro/nano (two-tier) structures are often employed to achieve superhydrophobicity. In condensation, utilizing such a surface is not necessarily advantageous because the macroscopically observed Cassie droplets are usually in fact partial Wenzel in condensation. The increase in contact angle through introducing microstructures on such two-tier roughened surfaces may result in an increase in droplet departure diameter and consequently deteriorate the performance. In the meantime, nanostructure roughened surfaces could potentially yield efficient shedding of liquid droplets, whereas microstructures roughened surfaces often lead to highly pinned Wenzel droplets. To attain efficient shedding of liquid droplets in condensation on a superhydrophobic surface, a Bond number (a dimensionless number for appraising drop-wise condensation) and a solid-liquid fraction smaller than 0.1 and 0.3, respectively, are suggested.
COGNITIVE RADIO COMMUNICATION SYSTEM AND OPERATING METHOD THEREOF
(2014-08-28)
WU Sau-Hsuan
;
Chao Hsi-Lu
;
Ko Chun-Hsien
;
Mo Shang-Ru
;
Jiang Chang-Ting
A cognitive radio communication network is provided. The cognitive radio communication network includes a cloud and a wireless communication network.A communication system accessing to a backbone network is provided. The communication system includes a cloud and a wireless communication network connected to the cloud, and having a plurality of cognitive radio access points and a plurality of users, wherein the cloud performs the functions of network management, power control, and radio resource management.
Facile electrochemical synthesis of 3D nano-architectured CuO electrodes for high-performance supercapacitors
(2014-08-28)
Deng, Ming-Jay
;
Wang, Cheng-Chia
;
Ho, Pei-Jung
;
Lin, Chih-Ming
;
Chen, Jin-Ming
With a simple electrochemical process, we prepared nano-architectured CuO electrodes with a 3D hierarchically porous structure and an excellent supercapacitive performance. These nano-architectured CuO electrodes were processed through co-deposition of a Ni-Cu layer on Ni foam, selective etching of Cu from the Ni-Cu film (leaving tentacle-like nanoporous Ni), and anodic deposition of CuO nanoribbons (NRs) on the tentacle-like nanoporous Ni/Ni foam substrate. Because of its unique nano-architecture, the prepared CuO nanoribbon-on-Ni-nanoporous/Ni foam (CNRNP) electrode shows exceptional performance of energy storage relative to a conventional version of the electrode. The CNRNP electrode has also a superior kinetic performance relative to CuO nanoflake-on-Ni foam (CNFNF) and flake-like CuO (FLC) electrodes. Besides its excellent cyclic stability, an exceptionally large specific capacitance of 880 and 800 F g(-1) (deducting the substrate capacitance from the total) for the CNRNP electrode is obtained at scan rates of 10 and 200 mV s(-1), respectively. The excellent pseudocapacitive characteristics of CNRNP electrodes associated with the variation of the Cu oxidation state during charge and discharge cycles were elucidated with in situ X-ray absorption near-edge structure (XANES) spectra.
Nonemptiness problems of Wang tiles with three colors
(2014-08-28)
Chen, Hung-Hsun
;
Hu, Wen-Guei
;
Lai, De-Jan
;
Lin, Song-Sun
;
應用數學系
This investigation studies nonemptiness problems of plane edge coloring with three colors. In the edge coloring (or Wang tiles) of a plane, unit squares with colored edges that have one of p colors are arranged side by side such that the touching edges of the adjacent tiles have the same colors. Given a basic set B of Wang tiles, the nonemptiness problem is to determine whether or not Sigma(B) not equal empty set , where Sigma(B) is the set of all global patterns on Z(2) that can be constructed from the Wang tiles in B. Wang's conjecture is that for any B of Wang tiles, Sigma (B) not equal empty set if and only if P(B) not equal empty set, where P(B) is the set of all periodic patterns on Z(2) that can be generated by the tiles in B. When p >= 5, Wang's conjecture is known to be wrong. When p = 2, the conjecture is true. This study proves that when p = 3, the conjecture is also true. If P(B) not equal empty set, then B has a subset B' of minimal cycle generators such that P(B') not equal empty set and P(B '') not equal empty set for B '' B'. This study demonstrates that the set C(3) of all minimal cycle generators contains 787, 605 members that can be classified into 2, 906 equivalence classes. N(3) is the set of all maximal non-cycle generators: if B is an element of N(3), then P(B) not equal empty set and P((B) over tilde) not equal empty set for (B) over tilde B. Wang's conjecture is shown to be true by proving that B is an element of N(3) implies Sigma(B) = empty set. (C) 2014 Elsevier B.V. All rights reserved.
Franck-Condon factors perturbed by damped harmonic oscillators: Solvent enhanced X (1)A(g) <-> A(1)B(1u) absorption and fluorescence spectra of perylene
(2014-08-28)
Wang, Chen-Wen
;
Yang, Ling
;
Zhu, Chaoyuan
;
Yu, Jian-Guo
;
Lin, Sheng-Hsien
Damped harmonic oscillators are utilized to calculate Franck-Condon factors within displaced harmonic oscillator approximation. This is practically done by scaling unperturbed Hessian matrix that represents local modes of force constants for molecule in gaseous phase, and then by diagonalizing perturbed Hessian matrix it results in direct modification of Huang-Rhys factors which represent normal modes of solute molecule perturbed by solvent environment. Scaling parameters are empirically introduced for simulating absorption and fluorescence spectra of an isolated solute molecule in solution. The present method is especially useful for simulating vibronic spectra of polycyclic aromatic hydrocarbon molecules in which hydrogen atom vibrations in solution can be scaled equally, namely the same scaling factor being applied to all hydrogen atoms in polycyclic aromatic hydrocarbons. The present method is demonstrated in simulating solvent enhanced X (1)A(g) <-> A(1)B(1u) absorption and fluorescence spectra of perylene (medium-sized polycyclic aromatic hydrocarbon) in benzene solution. It is found that one of six active normal modes v10 is actually responsible to the solvent enhancement of spectra observed in experiment. Simulations from all functionals (TD) B3LYP, (TD) B3LYP35, (TD) B3LYP50, and (TD) B3LYP100 draw the same conclusion. Hence, the present method is able to adequately reproduce experimental absorption and fluorescence spectra in both gas and solution phases. (C) 2014 AIP Publishing LLC.
Nonemptiness problems of Wang tiles with three colors
(2014-08-28)
Chen, Hung-Hsun
;
Hu, Wen-Guei
;
Lai, De-Jan
;
Lin, Song-Sun
;
應用數學系
This investigation studies nonemptiness problems of plane edge coloring with three colors. In the edge coloring (or Wang tiles) of a plane, unit squares with colored edges that have one of p colors are arranged side by side such that the touching edges of the adjacent tiles have the same colors. Given a basic set B of Wang tiles, the nonemptiness problem is to determine whether or not Sigma(B) not equal empty set , where Sigma(B) is the set of all global patterns on Z(2) that can be constructed from the Wang tiles in B. Wang\'s conjecture is that for any B of Wang tiles, Sigma (B) not equal empty set if and only if P(B) not equal empty set, where P(B) is the set of all periodic patterns on Z(2) that can be generated by the tiles in B. When p >= 5, Wang\'s conjecture is known to be wrong. When p = 2, the conjecture is true. This study proves that when p = 3, the conjecture is also true. If P(B) not equal empty set, then B has a subset B\' of minimal cycle generators such that P(B\') not equal empty set and P(B \'\') not equal empty set for B \'\' B\'. This study demonstrates that the set C(3) of all minimal cycle generators contains 787, 605 members that can be classified into 2, 906 equivalence classes. N(3) is the set of all maximal non-cycle generators: if B is an element of N(3), then P(B) not equal empty set and P((B) over tilde) not equal empty set for (B) over tilde B. Wang\'s conjecture is shown to be true by proving that B is an element of N(3) implies Sigma(B) = empty set. (C) 2014 Elsevier B.V. All rights reserved.
Zebrafish WNK Lysine Deficient Protein Kinase 1 (wnk1) Affects Angiogenesis Associated with VEGF Signaling
(2014-08-29)
Lai, Ju-Geng
;
Tsai, Su-Mei
;
Tu, Hsiao-Chen
;
Chen, Wen-Chuan
;
Kou, Fong-Ji
The WNK1 (WNK lysine deficient protein kinase 1) protein is a serine/threonine protein kinase with emerging roles in cancer. WNK1 causes hypertension and hyperkalemia when overexpressed and cardiovascular defects when ablated in mice. In this study, the role of Wnk1 in angiogenesis was explored using the zebrafish model. There are two zebrafish wnk1 isoforms, wnk1a and wnk1b, and both contain all the functional domains found in the human WNK1 protein. Both isoforms are expressed in the embryo at the initiation of angiogenesis and in the posterior cardinal vein (PCV), similar to fms-related tyrosine kinase 4 (flt4). Using morpholino antisense oligonucleotides against wnk1a and wnk1b, we observed that wnk1 morphants have defects in angiogenesis in the head and trunk, similar to flk1/vegfr2 morphants. Furthermore, both wnk1a and wnk1b mRNA can partially rescue the defects in vascular formation caused by flk1/vegfr2 knockdown. Mutation of the kinase domain or the Akt/PI3K phosphorylation site within wnk1 destroys this rescue capability. The rescue experiments provide evidence that wnk1 is a downstream target for Vegfr2 (vascular endothelial growth factor receptor-2) and Akt/PI3K signaling and thereby affects angiogenesis in zebrafish embryos. Furthermore, we found that knockdown of vascular endothelial growth factor receptor-2 (flk1/vegfr2) or vascular endothelial growth factor receptor-3 (flt4/vegfr3) results in a decrease in wnk1a expression, as assessed by in situ hybridization and q-RT-PCR analysis. Thus, the Vegf/Vegfr signaling pathway controls angiogenesis in zebrafish via Akt kinase-mediated phosphorylation and activation of Wnk1 as well as transcriptional regulation of wnk1 expression.
Zebrafish WNK Lysine Deficient Protein Kinase 1 (wnk1) Affects Angiogenesis Associated with VEGF Signaling
(2014-08-29)
Lai, Ju-Geng
;
Tsai, Su-Mei
;
Tu, Hsiao-Chen
;
Chen, Wen-Chuan
;
Kou, Fong-Ji
The WNK1 (WNK lysine deficient protein kinase 1) protein is a serine/threonine protein kinase with emerging roles in cancer. WNK1 causes hypertension and hyperkalemia when overexpressed and cardiovascular defects when ablated in mice. In this study, the role of Wnk1 in angiogenesis was explored using the zebrafish model. There are two zebrafish wnk1 isoforms, wnk1a and wnk1b, and both contain all the functional domains found in the human WNK1 protein. Both isoforms are expressed in the embryo at the initiation of angiogenesis and in the posterior cardinal vein (PCV), similar to fms-related tyrosine kinase 4 (flt4). Using morpholino antisense oligonucleotides against wnk1a and wnk1b, we observed that wnk1 morphants have defects in angiogenesis in the head and trunk, similar to flk1/vegfr2 morphants. Furthermore, both wnk1a and wnk1b mRNA can partially rescue the defects in vascular formation caused by flk1/vegfr2 knockdown. Mutation of the kinase domain or the Akt/PI3K phosphorylation site within wnk1 destroys this rescue capability. The rescue experiments provide evidence that wnk1 is a downstream target for Vegfr2 (vascular endothelial growth factor receptor-2) and Akt/PI3K signaling and thereby affects angiogenesis in zebrafish embryos. Furthermore, we found that knockdown of vascular endothelial growth factor receptor-2 (flk1/vegfr2) or vascular endothelial growth factor receptor-3 (flt4/vegfr3) results in a decrease in wnk1a expression, as assessed by in situ hybridization and q-RT-PCR analysis. Thus, the Vegf/Vegfr signaling pathway controls angiogenesis in zebrafish via Akt kinase-mediated phosphorylation and activation of Wnk1 as well as transcriptional regulation of wnk1 expression.
Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method
(2014-08-29)
Tsai, Wan-Lin
;
Wang, Kuang-Yu
;
Chang, Yao-Jen
;
Li, Yu-Ren
;
Yang, Po-Yu
For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400 degrees C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Omega/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.
Multiplex stimulated Raman imaging with white probe-light from a photonic-crystal fibre and with multi-wavelength balanced detection
(2014-08-30)
Seto, K.
;
Okuda, Y.
;
Tokunaga, E.
;
Kobayashi, T.
;
電子物理學系
A straightforward method for spectral stimulated Raman scattering (SRS) microscopy is to measure the scanned gain/loss spectrum of a white probe light from a photonic crystal fibre (PCF). However, the intensity of the white light noise is a serious problem for SRS microscopy. In this study, we have demonstrated simultaneous two-wavelength SRS microscopy with PCF through balanced detection suitable for spectroscopy with a modification of an auto-balance scheme. The developed auto-balance detection system suppresses the degradation of noise cancellation performance caused by a sample, and is suitable for spectral SRS imaging with simple and robust optics.
Studies on the photocatalysis of core-shelled SiO2-Ag nanospheres by controlled surface plasmon resonance under visible light
(2014-08-30)
Pan, Ko-Ying
;
Liang, Yi-Fan
;
Pu, Ying-Chih
;
Hsu, Yung-Jung
;
Yeh, Jien-Wei
Abundant core-shelled silica-silver nanospheres with uniform diameter and morphology were successfully synthesized by Stober and seed-mediated method, in sequence. By the different additions of glucose, the silver nanoparticles were deposited on silica spheres by redox reaction, which well controlled in the range from 10 to 50 nm. The surface plasmon resonance absorption band shifted toward infra-red region and became broader gradually during the dimensions of silver nanoparticles were increased in the growth range. The amazing data imply that using core-shelled silica-silver nanospheres efficiently enhances the degradation of the organic pollutants under solar energy, which means the core-shelled silica-silver nanospheres is not only a cost-effective route but an energy-saving way to our planet. (C) 2014 Elsevier B.V. All rights reserved.
Structural imperfections and attendant localized/itinerant ferromagnetism in ZnO nanoparticles
(2014-08-30)
Yang, Chao-Yao
;
Lu, Yi-Hsuan
;
Lin, Wei-Hao
;
Lee, Min-Han
;
Hsu, Yung-Jung
Using synchrotron-based x-ray magnetic spectroscopy, we report a study focusing on the local symmetry of Cu-dopant and resultant structural imperfections in mediating Cu-doped ZnO nanoparticles\' ferromagnetism (FM). Prepared by an antisolvent method, Cu appeared to preferably populate on the basal plane of ZnO with a local symmetry of [CuO4]. This unique symmetry was antiferromagnetic in nature, while electronically and structurally coupled to surrounded oxygen vacancies (V-o) that yielded a localized FM, because of a strong dependency on the number/location of the [CuO4] symmetry. Surprisingly, the FM of undoped but oxygen-deficient ZnO appeared to be more itinerant and long-range, where V-o percolated the FM effectively and isotropically through oxygen\'s delocalized orbital. By adopting the approach of structural imperfection, this study clearly identifies V-o\'s (defect\'s) true characters in mediating the FM of magnetic semiconductors which has been thought of as a long-standing debate, and thus provides a different thinking about the traditional extrinsic ferromagnetic-tuning in the semiconductors. It even illuminates recent research concerning the intrinsic FM of low-dimensional systems that contain defects but non-magnetic elements.