This paper presents L₁-adaptive controller for controlling uncertain parameters and time-varying unknown parameters to control the position of a DC servomotor. For the purpose of comparison, the effectiveness of L₁-adaptive controller for position control of studied servomotor has been examined and compared with another adaptive controller; Model Reference Adaptive Controller (MRAC). Robustness of both L₁-adaptive controller and model reference adaptive controller to different input reference signals and different structures of uncertainty were studied. Three different types of input signals are taken into account; ramp, step and sinusoidal. The L₁-adaptive controller ensured uniformly bounded

Piezoelectric structures are nowadays used in many different applications. A better understanding of the influence of material properties and geometrical design on the performance of these structures helps to develop piezoelectric structures specifically designed for their application. Different equivalent circuits have been introduced in the literature to investigate the behaviour of piezoelectric transducers. The model parameters are usually determined from measurements covering the characteristic frequencies of the piezoelectric transducer. This article introduces an analytical technique for calculating the mechanical and electrical equivalent system parameters and characteristic frequencies based on material properties and geom

Evolutionary·co.nipimit'iQo  is  a· c'!a s of glbbal ·searb  techniq

based on the lei.lffi:ing process ,of  g po_pl)'latiog-·of pote.n:tiaf solutions to

a  ven probl_e-ID'.  thahas .been  succe_ssfull'y  applied    19  v ety of

prQblern, lll thls paper a riew approach  to. design lie_ ural ne'twQj:ks

based oh ev.ohltipnary -computa.tio.rt i·s pre.Seri-L  _A   tine-f.!£ clurP.mosome

'repr:esentati:on  or the etwor}< i_s.  u_secl: 'Q.y  genetiC  gperntb_l:s, whicQ

allow th¢  voJution of.the   chitecture and' weight-s Â

Background: This study was conducted to evaluate the surface roughness and dimensional accuracy of commercially obtainable alginate impression material in terms of imbibition after immersion in two different media. Materials and method: Two disinfecting agents, ethanol 70% and povidone-iodine 4%, were used to access the dimensional accuracy and surface roughness of alginate impression material. Weights of specimen discs of alginate impressions were measured before and immediately after immersion to gain a measure of imbibition. For surface roughness, disinfected specimens rectangle was examined before and after disinfection. Results: Minimal changes in weight were observed after disinfection, but a statistically non-significant differenc

Oilwell cementing operations are crucial for drilling and completion, preserving the well's productive life. However, weak and permeable formations pose a high risk of cement slurry loss, leading to failure. Lightweight cement, like foamed cement, is used to avoid these difficulties. This study is focused on creating a range of foamed slurry densities and examining the effect of gas concentration on their rheological properties. The foaming agent and foam stabilizer are tested, and the optimal concentration is determined to be 2% and 0.12%, respectively, by the weight of the cement.

Furthermore, the construction of samples of foam cement with different densities (0.8, 1.0, 1.2, 1.4, and 1.6) g/cc is performed to f

This  study  was undertaken  to shed light on the changes  of levels of CP

activity, Cu and  Fe in sera of .(53) normaJ non-smoker pregnant's  without complication, during  three1rimestcrs of pregnancy.

G1  inc.l_ude  (I 8) pre nants in  the 1' 1 tri nester, G2 19)  pret:,rp:all.ts  _wear

taken     m the  2"    tnmester  and  G3  (16) pregnants  m the  3rd  trunester.

/\nothe.r ('18) ·serum samples were taken from liealthy non-pregnant wqmen

age matched as control·group G4.

Results bowed a significant steady  elevation in CP .p:ctivity and &n

The main objective of this study is to develop predictive models using SPSS software (version 18) for Marshall Test results of asphalt mixtures compacted by Hammer, Gyratory, and Roller compaction. Bulk density of (2.351) gm/cc, at OAC of (4.7) % was obtained as a benchmark after using Marshall Compactor as laboratory compactive effort with 75-blows. Same density was achieved by Roller and Gyratory Compactors using its mix designed methods.

A total of (75) specimens, for Marshall, Gyratory, and Roller Compactors have been prepared, based on OAC of (4.7) % with an additional asphalt contents of more and less than (0.5) % from the optimum value. All specimens have been subjected to Marshall Test. Mathematical model

       The dielectric properties of polyvinyl chloride (PVC)-MnCl2 composite were studied by using the impedance technique. The measurements were carried out as a function of frequency in the range from 10 Hz to 13 MHz and temperature range from 27oC to 55oC. Using a composite of 20 wt. % MnCl2 by weight, it was found that the dielectric constants and the dielectric loss of the prepared films increase with the increasing temperature at law frequency and the enhancement of the ionic conduction which is confirmed by the increase the of AC. conductivity and the decrease of the activation energy of the conduction mechanism at high applied frequency. The observed relaxation and polarization effects of composite a

A new ligand [N-(acetyl amino) thioxomethyl] valine was prepared from the reaction of acetyl iso thiocyanate with valine. The ligand was characterized by FT-IR, UV- vis and 1HNMR spectrum, The complexes with some metal ions (M +2 =Co,Ni,Cu,Zn,Cd,Hg) have been prepared and characterized. The structural diagnosis were established by IR,UV-Vis  spectrum, flame atomic absorption spectroscopy conductivity and magnetic susceptibility ,the complexes showed tetrahedral geometry around the metal   l.