scholarly journals Temperature analysis of driver and optical behavior of LED lamps

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Emerson Roberto Santos ◽  
Maurício Vicente Tavares ◽  
Antonio Celso Duarte ◽  
Hélio Akira Furuya

This exploratory study was carried out with the objective to know the optical behavior of light-emitting diode (LED) lamps used and the temperature reached by electronic components that compose the driver (electronic circuit situated inside the body LED lamp) responsible to convert electrical alternating current from power line to direct current to operate the LED devices. Then, two different experiments were carried out with LED lamps. In the first experiment, 131 LED lamps used were chosen randomly and bought from household appliances store (bargain market product) presenting different nominal powers, 8, 10, 12 and 15 watts. All LED lamps were polarized at the power line at 127 V and revealed different optical behaviors, such as: not turn-on; flashing light (as strobe effect); flashing light (as strobe effect) with high intensity (more intense than normal); flashing light (as strobe effect) with low intensity (less intense than normal); fast turnon and turn-off only; and turn-on with low intensity of light (less intense than normal). The hypothesis for these behaviors can be attributed by three different behaviors: in lamps not turn-on, this failure can be attributed for dark spots that are created on the surface of LED device. In these lamps, all LED devices are electrically connected in serial. When a LED is inoperative, the electrical current is interrupted for all LED devices; damage to the electronic components caused by internal high temperature confined inside the lamp body during the operation causing electrical oscillations, as observed from different behaviors from flashing light, flashing light with high intensity, flashing light with low intensity and fast turn-on and turn-off only; swelling of the electrolytic capacitors causing low energy storage and varying the electrical current flow, the electrical current for other electronic components altered the normal optical behavior of the LED lamps. In the second experiment, the temperatures of electronic components located in driver were obtained out of body lamp revealing: from 33 (lowest temperature attributed to inductor) to 52.5ºC (highest temperature attributed to electrolytic capacitor). These temperature values represent the ideal or normal condition of operation for electronic components, but, when they are operating inside the lamp body, the found temperature values increased considerably. This characteristic can be better evidenced by strong color change (caused by accumulative temperature during the elapsed days used) on the printed circuit board used in the driver.

Author(s):  
Carpio-Rivera E ◽  
Moncada-Jiménez J ◽  
Salazar-Roja W ◽  
Araya-Vargas G

The purpose of the study was to evaluate the acute effect of different intensity aerobic (AE) and resistance training (RT) exercises on BI in adult women. Participants were 62 adult women (19.47 ± 2.53 yr., range 18 a 33 yr.), who were randomly assigned to three sessions of either: 1) Control group, 2) Low-intensity AE, 3) High-intensity AE, 4) Low-intensity RT, or 5) High-intensity RT. Before and immediately following each experimental intervention, BI, body weight, and arm and leg circumferences were measured. Three familiarization sessions were performed every 7 days before the AE and RT experimental interventions. Also, 5-RM tests were performed one week before the RT experimental interventions. Data were analyzed using mixed 3-way ANOVA, mixed 4-way ANOVA, and post-hoc analysis. An acute effect of RT on BI was observed, regardless of the exercise intensity, women felt more muscular immediately following the RT session. Regardless of the exercise intensity, 30-min of acute RT exercise changed BI perception, contrary to 30 min AE.


Behaviour ◽  
1977 ◽  
Vol 61 (3-4) ◽  
pp. 238-274 ◽  
Author(s):  
Michael N. Lehman ◽  
David B. Adams

AbstractThe behavior sequences of male rats during tests for isolation-induced fighting were analyzed by computer. All transitional dyads which were highly significant (probability less than .001 by chance) were listed in tables and categorized. Most highly significant transition dyads fell into five categories: exploration and scent-marking; grooming; defense and submission; offense, and approach and retreat. All of these categories were obtained for sequences within the home rat, within the intruder rat, and between the two rats except for the following: offense sequences were seen only in the home rat; approach and retreat sequences were seen only in interactions; and interaction sequences usually involved combinations of offense with defense or submission rather than simple offense sequences or simple defense-submission sequences. Further analysis of exploration and scent-marking dyads suggested that the various acts and postures all reflect a single underlying motivational mechanism which activates motor patterning mechanisms whose motor patterns are directed by continually changing orientation towards different objects in the environment. The ratios of obtained to expected frequency of transition from one act or posture to another were usually symmetrical and most of the possible dyads were observed in frequencies greater than expected by chance. Analysis of grooming dyads also suggested that these acts and postures reflect a single underlying motivational mechanism which activates motor patterning mechanisms through which directing stimuli orient grooming towards various parts of the animal's own body or the body of the opponent. Within self-grooming most of the possible dyads were observed at frequencies greater than expected by chance, and the transition ratios were symmetrical. It was suggested that these behaviors all facilitate the broadcast diffusion of odors from scent glands on the face, flank, and ano-genital region, that the motivational mechanism is activated by sensations arising from these glands which are differentially activated by way of other motivational mechanisms, and that self-grooming might also be characterized as "self-anointing". Offense behaviors of the home rat tended to follow an asymmetrical sequence: from sniff-dish and crawl-over-dish to repeated offensive sideways posture to full aggressive posture to bite-and-kick attack, with the latter act followed by a refractory period. The frequent initiation of the sequence by sniff-dish behavior was taken as evidence that an offense motivational mechanism is activated by comparison of strange rat odors with familiar home cage odors. A number of acts and postures were considered to be ambivalent or hybrids of motor patterns produced by patterning mechanisms simultaneously activated by offense and other motivational mechanisms. These include aggressive groom and rub (grooming and offense), crawl-under (exploration and offense), and offensive sidoeways posture, upright posture and boxing (both offense and defense). A detailed analysis of the many dyads from offense behavior to defense and submissive behaviors led to the following hypothesis. There are probably two different motivational mechanisms, defense and submission, which are activated by stimuli associated with attack by the opponent, dorsal tactile stimulation or an elevated approach. Both defense and submission are elicited by dorsal tactile stimulation and both are potentiated following subjection to attack. Defense, but not submission, may also be elicited by a high approach of the opponent. The motor patterns of defense are flight in a large enclosure, or high postures in a confined space. The high postures are usually of low intensity (sideways posture) if the motivating stimuli are of low intensity and if the motivational mechanism is not sensitized by previous attack. They are usually of high intensity (upright postures) if the motivating stimuli are of high intensity or if the motivational mechanisms has been sensitized by attack. The submissive postures may also be of low intensity (crouch) or high intensity (full submissive posture) depending upon intensity of motivating stimuli and sensitization by pain. Submission often includes the emission of a 25 kilo herz ultrasound cry which inhibits further attack by the opponent. An alternative hypothesis was considered: that submission and defense are sets of motor patterning mechanisms, each activated by a single motivation mechanism but differentiated by different releasing stimuli. In addition to the primary significant transitional dyads mediated by five motivational mechanisms, there were also many secondary and tertiary transitional dyads obtained as a result of the temporal correspondence of two different acts or postures each elicited as primary effects from another behavioral act or posture which preceded both of them. These secondary and tertiary effects, less significant than the primary effects, could be demonstrated by triangulation in flowcharts of the behaviors. Practically all of the 105 highly significant behavioral transition dyads in the tests could be explained as primary effects due to the action of only five basic motivational mechanisms and the secondary or tertiary effects based on these primary effects. The five motivational mechanisms were identified as: exploration and scent-marking; grooming, offense; defense; and submission. A model was presented which included these five motivational mechanisms, their critical stimulus inputs (motivational stimuli), the motor patterning mechanisms which they activate and which receive separate input from releasing and directing stimuli. Specific acts and postures could be understood as simple or complex combinations of motor patterns which were produced by motor patterning mechanisms activated by single or multiple combinations of motivational mechanisms.


1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.


1997 ◽  
Vol 77 (04) ◽  
pp. 685-689 ◽  
Author(s):  
Paul A Kyrle ◽  
Johannes Brockmeier ◽  
Ansgar Weltermann ◽  
Sabine Eichinger ◽  
Wolfgang Speiser ◽  
...  

SummaryCoumarin-induced skin necrosis is believed to be due to a transient hypercoagulable state resulting from a more rapid decline of the protein C activity relative to that of coagulation factors (F) II, IX and X during initiation of oral anticoagulant therapy. We studied hemostatic system activation during early oral anticoagulant treatment with a technique that investigates coagulation activation in the microcirculation.We determined in 10 healthy volunteers the concentrations of prothrombin fragment F1+2 (f1.2) and thrombin-antithrombin complex (TAT) in blood emerging from an injury of the microvasculature (bleeding time incision) before and after initiation of both high-inten- sity and low-intensity coumarin therapy. In addition, f1.2, TAT, activated F VII (F Vila) and the activities of FII, F VII, F X and protein C were measured in venous blood.A rapid decline of F VII and protein C was observed in venous blood with activities at 24 h of 7 ± 1% and 43 ± 2%, respectively, during the high-intensity regimen. A 20 to 30% reduction of f1.2 and TAT was seen in venous blood at 72 h with no major difference between the high- and the low-intensity regimen. F Vila levels were substantially affected by anticoagulation with a >90% reduction at 48 h during the high-intensity regimen. Following high-intensity coumarin, a >50% decrease in the fl.2 and TAT levels was found in shed blood at 48 h suggesting substantial inhibition of thrombin generation during early oral anticoagulation. An increase in the f1.2 and TAT levels was seen neither in shed blood nor in venous blood.Our data do not support the concept of a transient imbalance between generation and inhibition of thrombin as the underlying pathomechanism of coumarin-induced skin nekrosis.


Author(s):  
Goncalo V. Mendonca ◽  
Carolina Vila-Chã ◽  
Carolina Teodósio ◽  
André D. Goncalves ◽  
Sandro R. Freitas ◽  
...  

2020 ◽  
Vol 47 (1) ◽  
Author(s):  
Rabab S. Zaghlol ◽  
Sahar S. Khalil ◽  
Ahmed M. Attia ◽  
Ghada A. Dawa

Abstract Background Total knee replacement operation (TKR) is the treatment of choice in severe knee osteoarthritis (OA). Rehabilitation post-TKR is still not well studied. The aim of this study was to compare between the high-intensity (HI) rehabilitation program and the low-intensity (LI) rehabilitation program following TKR. Results At 1 month following the TKR operations, significant improvements were found in the first group compared to the second group in all the measured parameters except for the knee range of motion (ROM). At 3 and 12 months follow-up periods, there were statistically significant differences between both groups in all the evaluated parameters except for the numeric pain rating scale and the knee ROM. Conclusions Both high-intensity and low-intensity rehabilitation programs are effective; however, HI program had superior functional gain and patient-reported outcomes compared to the LI program. Moreover, HI group has a long-term functional gain.


2020 ◽  
pp. 108201322097379
Author(s):  
Jahir Antonio Barajas-Ramírez ◽  
Ana Luisa Gutiérrez-Salomón ◽  
Sonia Guadalupe Sáyago-Ayerdi

The calyces of roselle ( Hibiscus sabdariffa L.) are used to make a refreshing drink with high content of anthocyanins and other phenolic compounds, although the process for obtaining the beverage is not standardized. In this research it was determined physicochemical characteristics, total soluble polyphenols content, antioxidant activity and acceptance for beverages prepared by decoction at four concentrations of calyces in water (1.0, 2.5, 5.0 and 10.0%) and two concentrations of sucrose (11 and 16%). Color parameters in beverages permitted to describe them as red, which turned darker as the content of hibiscus increased. Total soluble polyphenols content and antioxidant activity were directly correlated with content of calyces in beverages and inversely correlated with pH, which means that beverages with higher content of calyces could be perceived as more acidic and more intense in characteristics associated with hibiscus presence, such as acid, astringent and the presence of intense dark red color, although the higher concentration of sucrose might have contributed to mask slightly the sourness and astringency. Acceptance for hibiscus beverages allowed to observe two segments of consumers, high-intensity and low-intensity likers but both confluence in overall liking values for beverages prepared with 2.5% calyces and 16% sucrose.


Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3353
Author(s):  
Marina Makrygianni ◽  
Filimon Zacharatos ◽  
Kostas Andritsos ◽  
Ioannis Theodorakos ◽  
Dimitris Reppas ◽  
...  

Current challenges in printed circuit board (PCB) assembly require high-resolution deposition of ultra-fine pitch components (<0.3 mm and <60 μm respectively), high throughput and compatibility with flexible substrates, which are poorly met by the conventional deposition techniques (e.g., stencil printing). Laser-Induced Forward Transfer (LIFT) constitutes an excellent alternative for assembly of electronic components: it is fully compatible with lead-free soldering materials and offers high-resolution printing of solder paste bumps (<60 μm) and throughput (up to 10,000 pads/s). In this work, the laser-process conditions which allow control over the transfer of solder paste bumps and arrays, with form factors in line with the features of fine pitch PCBs, are investigated. The study of solder paste as a function of donor/receiver gap confirmed that controllable printing of bumps containing many microparticles is feasible for a gap < 100 μm from a donor layer thickness set at 100 and 150 μm. The transfer of solder bumps with resolution < 100 μm and solder micropatterns on different substrates, including PCB and silver pads, have been achieved. Finally, the successful operation of a LED interconnected to a pin connector bonded to a laser-printed solder micro-pattern was demonstrated.


2014 ◽  
Vol 42 (6) ◽  
pp. 760-764 ◽  
Author(s):  
Katharine A. Rimes ◽  
Janet Wingrove ◽  
Rona Moss-Morris ◽  
Trudie Chalder

Background: Cognitive behavioural interventions are effective in the treatment of chronic fatigue, chronic fatigue syndrome (sometimes known as ME or CFS/ME) and irritable bowel syndrome (IBS). Such interventions are increasingly being provided not only in specialist settings but in primary care settings such as Improving Access to Psychological Therapies (IAPT) services. There are no existing competences for the delivery of “low-intensity” or “high-intensity” cognitive behavioural interventions for these conditions. Aims: To develop “high-intensity” and “low-intensity” competences for cognitive behavioural interventions for chronic fatigue, CFS/ME and IBS. Method: The initial draft drew on a variety of sources including treatment manuals and other information from randomized controlled trials. Therapists with experience in providing cognitive behavioural interventions for CF, CFS/ME and IBS in research and clinical settings were consulted on the initial draft competences and their suggestions for minor amendments were incorporated into the final versions. Results: Feedback from experienced therapists was positive. Therapists providing low intensity interventions reported that the competences were also helpful in highlighting training needs. Conclusions: These sets of competences should facilitate the training and supervision of therapists providing cognitive behavioural interventions for chronic fatigue, CFS/ME and IBS. The competences are available online (see table of contents for this issue: http://journals.cambridge.org/jid_BCP) or on request from the first author.


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