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On delay differential equations with meromorphic solutions of hyper-order less than one
Risto Korhonen,Yan Liu 대한수학회 2024 대한수학회보 Vol.61 No.1
We consider the delay differential equations \begin{equation*} b(z)w(z+1)+c(z)w(z-1)+a(z)\frac{w'(z)}{w^k(z)}=\frac{P(z,w(z))}{Q(z,w(z))}, \end{equation*} where $k\in\{1,2\}$, $a(z)$, $b(z)\not\equiv 0$, $c(z)\not\equiv 0$ are rational functions, and $P(z,w(z))$ and $Q(z,w(z))$ are polynomials in $w(z)$ with rational coefficients satisfying certain natural conditions regarding their roots. It is shown that if this equation has a non-rational meromorphic solution $w$ with hyper-order $\rho_{2}(w)<1$, then either $\deg_w(P)=\deg_w(Q)+1\leq 3$ or $\max\{\deg_w(P),\deg_w(Q)\}\leq 1$. In addition, it is shown that in the case $\max\{\deg_w(P),\deg_w(Q)\}= 0$ the equations above can have such a solution, with an additional zero density requirement, only if the coefficients of the equation satisfy certain strict conditions.
( Risto Laulajainen ) 한국EU학회 2014 Asia-Pacific Journal of EU Studies Vol.12 No.1
Various worldwide foreland regionalizations are developed for Handysize-product tankers. Based on this experience, the selected technique is extended to the remaining six product and crude oil segments. Since no clear inflection points can be found for the Handysize agglomeration coefficients of hierarchical clustering methods, non-hierarchical methods are used instead. When using these methods, each segment needs an estimate of the clusters toward which the aggregation proceeds. These seed numbers are found by analyzing the 31×31 trade matrices. Alternatively, principles used for the delimitation of city trade areas are applied (dominance). The estimates are preferably table squares but, in larger size classes, strings are also accepted. The derived clusters tally broadly with the heuristics, but have the advantage that they cover all the oceans and are not overly sensitive to small trade flows. The results are rather unique about a topic hardly ever discussed.
Yasuhiro Senda,Janne Blomqvist,Risto M. Nieminen 한국진공학회 2017 Applied Science and Convergence Technology Vol.26 No.1
We investigated the stability of ionic configurations of the tip of the cantilever in non-contact AFM.; For this, we used a computational model that couples the ionic motion of the MgO surface and the oscillating cantilever. The motion of ions was connected to the oscillating cantilever using a coupling method that had been recently developed. The adhesive process on the ionic MgO surface leads to energy dissipation of the cantilever. It is shown that limited types of ionic configurations of the tip are stable during the adhesive process. Based on the present computational model, we discuss the adhesive mechanism leading to energy dissipation.
Wireless Machine-to-Machine Healthcare Solution Using Android Mobile Devices in Global Networks
Jung, Sang-Joong,Myllyla, Risto,Chung, Wan-Young IEEE 2013 IEEE SENSORS JOURNAL Vol.13 No.5
<P>This paper presents a prototype machine-to-machine (M2M) healthcare solution that combines mobile and IPv6 techniques in a wireless sensor network to monitor the health condition of patients and provide a wide range of effective, comprehensive, and convenient healthcare services. A low-power embedded wearable sensor measures the health parameters dynamically, and is connected, according to the concept of IPv6 over low-power wireless personal area network, to the M2M node for wireless transmission through the internet or external IP-enabled networks via the M2M gateway. A visualization module of the server program graphically displays the recorded biomedical signals on Android mobile devices used by patients and doctors at the end of the networks in real-time. Our approach for a global M2M healthcare solution is managed to process the large amount of biomedical signals through the extended network combining IPv6 technique and mobile technology for daily lifestyle to users appropriately.</P>
Leena Malinen,Eveliina Repo,Risto Harjula,Nina Huittinen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.2
In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste isneeded to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organiccomplexing agents such as EDTA cobalt removal can be problematic due to the high stability of the CoEDTA complex. In this study, the removal of cobalt from NaNO3 solutions using antimony oxide (Sb2O3)synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence ofEDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UVlight) and under UV-C irradiation. Ca2þ or Ni2þ were included in the experiments as competing cations totest the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances thecobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption ofcobalt to a higher extent than calcium. Finally, the sorption data collected for Co2þ on antimony oxidewas modeled using six different isotherm models. The Sips model was found to be the most suitablemodel to describe the sorption process. The Dubinin-Radushkevich model was further used to calculatethe adsorption energy, which was found to be 6.2 kJ mol1
Senda, Yasuhiro,Blomqvist, Janne,Nieminen, Risto M. The Korean Vacuum Society 2017 Applied Science and Convergence Technology Vol.26 No.1
We investigated the stability of ionic configurations of the tip of the cantilever in non-contact AFM.; For this, we used a computational model that couples the ionic motion of the MgO surface and the oscillating cantilever. The motion of ions was connected to the oscillating cantilever using a coupling method that had been recently developed. The adhesive process on the ionic MgO surface leads to energy dissipation of the cantilever. It is shown that limited types of ionic configurations of the tip are stable during the adhesive process. Based on the present computational model, we discuss the adhesive mechanism leading to energy dissipation.
Tapio E. J. Fabritius,Shuichi Makita,Masahiro Yamanari,Risto A. Myllylä,Yoshiaki Yasuno 한국광학회 2011 Current Optics and Photonics Vol.15 No.2
Full-range spectral domain optical coherence tomography (SD-OCT) with a 1-μm band light source is shown here. The phase of the reference beam is continuously stepped while the probing beam scans the sample laterally (B-scan). The two dimensional spectral interferogram obtained is processed by a Fourier transform method to obtain a complex spectrum leading to a full-range OCT image. A detailed mathematical explanation of the complex conjugate resolving method utilized is provided. The system’s measurement speed was 7.96 kHz, the measured axial resolution was 9.6 μm in air and the maximum sensitivity 99.4dB. To demonstrate the effect of mirror image elimination, In vivo human eye pathology was measured.