Kompenzacija sustava s rezonancijom i vremenskim kašnjenjem pomoću valnog kompenzatora

Recently, teleoperated robots have been researched for working in ultimate environment actively. Developing performance of teleoperated robots, it will be possible for human to work in such a ultimate environment with safety. However, in the actual case, a flexible mechanism caused by the mechanical constraint such as weight saving of robot, using gear, and so on, induces vibration. Moreover, a communication delay causes vibration, too. In addition, in the worst case, the delay makes the control system unstable. Therefore, in this paper, for suppressing the vibration, compensation of integrated resonant and time-delay systems by using a wave compensator is proposed. In the proposal, there are two important control structures. Firstly, a reflected wave in the resonant system is eliminated by a reflected wave rejection. A transfer function of wave equation without the reflected wave is represented as a time delay. Therefore, a resonant system without a reflected wave can be regarded as an equivalent time-delay system. Next, it is defined that an effect of time delay from resonant and communication systems is caused by a time-delay disturbance. Then, vibrations from resonant and communication delays are simultaneously suppressed by the wave compensator. Finally, the validity of the proposal is verified by simulation and experimental results.U posljednje vrijeme daljinski upravljani roboti za rad u izazovnim okruženjima dobivaju na važnosti. Poboljšanje sposobnosti daljinski upravljanih robota neosporno bi omogućilo bi sigurniji rad u takvim okruženjima.Ipak, realne robotske konstrukcije često podrazumijevaju fleksibilne prijenosne mehanizme, zupčanike i druge elemente koji unose nepoželjne vibracije u sustav. Fenomen vibracije dodatno je naglašen i vremenskim kašnjenjem u komunikaciji s robotom što može u konačnici uzrokovati nestabilno ponašanje. U ovom se radu predlaže mehanizam sprječavanja vibracija temeljen na kompenzatoru valova. Mehanizam se sastoji od dvije cjeline. Prvi korak je eliminacija reflektiranog vala. Drugo, prijenosna funkcija valne jednadžbe bez reflektirano vala tretira se kao vremensko kašnjenje. Stoga se rezonantni sustav može promatrati može promatrati kao ekvivalentni sustav s vremenskim kašnjenjem. Nadalje, utjecaj se vremenskog kašnjenja modelira kao poremećaj s vremenskom odgodom. U konačnici se vibracije rezonantnog i komunikacijskog kašnjenja potiskuju kompenzatorom valova. Predloženi je algoritam ispitan u simulacijama kao i na stvarnome sustavu

Origin of Orthorhombic Transition, Magnetic Transition, and Shear Modulus Softening in Iron Pnictide Superconductors: Analysis based on the Orbital Fluctuation Theory

The main features in iron-pnictide superconductors are summarized as (i) the orthorhombic transition accompanied by remarkable softening of shear modulus, (ii) high-Tc superconductivity close to the orthorhombic phase, and (iii) stripe-type magnetic order induced by orthorhombicity. To present a unified explanation for them, we analyze the multiorbital Hubbard-Holstein model with Fe-ion optical phonons based on the orbital fluctuation theory. In the random-phase-approximation (RPA), a small electron-phonon coupling constant ($\lambda ~ 0.2$) is enough to produce large orbital (=charge quadrupole) fluctuations. The most divergent susceptibility is the $O_{xz}$-antiferro-quadrupole (AFQ) susceptibility, which causes the s-wave superconductivity without sign reversal (s_{++}-wave state). At the same time, divergent development of $O_{x2-y2}$-ferro-quadrupole (FQ) susceptibility is brought by the "two-orbiton process" with respect to the AFQ fluctuations, which is absent in the RPA. The derived FQ fluctuations cause the softening of $C_{66}$ shear modulus, and its long-range-order not only triggers the orthorhombic structure transition, but also induces the instability of stripe-type antiferro-magnetic state. In other words, the condensation of composite bosons made of two orbitons gives rise to the FQ order and structure transition. The theoretically predicted multi-orbital-criticality presents a unified explanation for abovementioned features of iron pnictide superconductors.Comment: 19 pages, 15 figure

Improving Teaching Methods, Student Learning Outcomes, and Curricula through Cross-Phase Teaching in Primary and Junior High School

In order to obtain a certain hint of forming a good cooperation between primary and junior high schools through Cross-Phase Teaching (CPT), it is necessary to verify the effect of CPT. We analyzed our CPT, surveyed the teachers and students by questionnaire, and interviewed the teachers, so that we might verify the effect of the CPT. While verifying, we not only recognized the change of the teachers' mind but also found the concrete way of improving their teaching

Recurrent advanced colonic cancer occurring 11 years after initial endoscopic piecemeal resection: a case report

<p>Abstract</p> <p>Background</p> <p>The high frequency of local recurrence occurring after endoscopic piecemeal resection (EPMR) for large colorectal tumors is a serious problem. However, almost all of these cases of local recurrence can be detected within 1 year and cured by additional endoscopic resection. We report a rare case of recurrent advanced colonic cancer diagnosed 11 years after initial EPMR treatment.</p> <p>Case presentation</p> <p>A 65-year-old male was diagnosed with a sigmoid colon lesion following a routine health check-up. Total colonoscopy revealed a 12 mm type 0-Is lesion in the sigmoid colon, which was diagnosed as an adenoma or intramucosal cancer and treated by EPMR in 1996. The post-resection defect was closed completely using metallic endoclips to avoid delayed bleeding. In 2007, at the third follow up, colonoscopy revealed a 20 mm submucosal tumor (SMT) like recurrence at the site of the previous EPMR. The recurrent lesion was treated by laparoscopic assisted sigmoidectomy with lymph node dissection.</p> <p>Conclusion</p> <p>When it is difficult to evaluate the depth and margins of resected tumors following EPMR, it is important that the defect is not closed in order to avoid tumor implantation, missing residual lesions and to enable earlier detection of recurrence. It is crucial that the optimal follow-up protocol for EPMR cases is clarified, particularly how often and for how long they should be followed.</p

Reduction of T-Box 15 gene expression in tumor tissue is a prognostic biomarker for patients with hepatocellular carcinoma

Genome-wide analysis is widely applied to detect molecular alterations during oncogenesis and tumor progression. We analyzed DNA methylation profiles of hepatocellular carcinoma (HCC), and investigated the clinical role of most heypermethylated of tumor, encodes T-box 15 (TBX15), which was originally involved in mesodermal differentiation. We conducted a genome-wide analysis of DNA methylation of tumor and non-tumor tissue of 15 patients with HCC, and revealed TBX15 was the most hypermethylated gene of tumor (Beta-value in tumor tissue = 0.52 compared with non-tumor tissue). Another validation set, which comprised 58 HCC with radical resection, was analyzed to investigate the relationships between tumor phenotype and TBX15 mRNA expression. TBX15 mRNA levels in tumor tissues were significantly lower compared with those of nontumor tissues (p < 0.0001). When we assigned a cutoff value = 0.5-fold, the overall survival 5-year survival rates of the low-expression group (n = 17) were significantly shorter compared with those of the high-expression group (n = 41) (43.3% vs. 86.2%, p = 0.001). Multivariate analysis identified low TBX15 expression as an independent prognostic factor for overall and disease-free survival. Therefore, genome-wide DNA methylation profiling indicates that hypermethylation and reduced expression of TBX15 in tumor tissue represents a potential biomarker for predicting poor survival of patients with HCC