637 research outputs found
ImageNet Large Scale Visual Recognition Challenge
The ImageNet Large Scale Visual Recognition Challenge is a benchmark in
object category classification and detection on hundreds of object categories
and millions of images. The challenge has been run annually from 2010 to
present, attracting participation from more than fifty institutions.
This paper describes the creation of this benchmark dataset and the advances
in object recognition that have been possible as a result. We discuss the
challenges of collecting large-scale ground truth annotation, highlight key
breakthroughs in categorical object recognition, provide a detailed analysis of
the current state of the field of large-scale image classification and object
detection, and compare the state-of-the-art computer vision accuracy with human
accuracy. We conclude with lessons learned in the five years of the challenge,
and propose future directions and improvements.Comment: 43 pages, 16 figures. v3 includes additional comparisons with PASCAL
VOC (per-category comparisons in Table 3, distribution of localization
difficulty in Fig 16), a list of queries used for obtaining object detection
images (Appendix C), and some additional reference
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A portfolio of compositions with commentary
This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London
A study of the effectiveness of two methods of teaching science in grades four, five and six
Thesis (Ed.D.)--Boston Universit
Investigating Student Understanding of Sound as a Longitudinal Wave
The field of physics education research (PER) has highlighted the discrepancy between what is taught during traditional instruction in physics, and what students understand afterward. PER has also provided alternatives to traditional instruction that are research-based and have been shown to be more effective in bringing studentsβ level of understanding of physics more in line with that of the scientific community. One topic that has received attention is the propagation of sound. We confirmed that students in the introductory algebra-based and calculus-based physics courses at the University of Maine have difficulties with sound propagation similar to those documented by others. We found that a relatively small percentage of the students we interviewed from a calculus-based introductory physics course used the community consensus model of particles oscillating parallel to the direction of propagation. We identified three other mental models used by the interview subjects that have been described previously. The first was a model in which sound is considered to be an entity that passes through the medium without disturbing the particles of the medium. The second was a model in which sound is viewed as an entity that pushes the particles of the medium aside as it propagates. The third was a hybrid model in which the particles of the medium oscillate perpendicular to the direction of propagation. In an extension of the work by previous researchers in this area, we examined studentsβ ability to predict the points at which the particles of the medium have the maximum and the minimum magnitudes of velocity and displacement from their equilibrium positions. We found that studentsβ ability to do so was extremely limited. To improve student understanding of sound propagation, we developed an instructional tool in the form of a βtutorialβ and evaluated its effectiveness through pre- and post-testing of students enrolled in an algebra-based introductory physics course. The tutorial constructed for this purpose was found to be successful in increasing the number of students that used the community consensus model when answering questions about sound propagation. It was less successful in enabling students to make accurate predictions about particle velocities and displacements
2008 Annual Research Symposium Abstract Book
2008 annual volume of abstracts for science research projects conducted by students at Trinity College
The use of stereolithography and related technologies to produce short run tooling
ThesisWhere material properties are critical to a polymer part, rapid prototype (RP) models are
inappropriate for evaluation purposes and actual parts moulded in a range of materials are
required for evaluation. Conventional tool making processes have extremely long lead times
considering that numerous iterations may be required. The aim of this project was to generate
polymer parts, utilising various approaches to Rapid Tooling (RT) , including Stereolithography
or related technologies, as part of the process. The objective was to establish decision-making
criteria for deciding on the appropriateness of various processes and the risks involved to assist
prospective users of these technologies.
The first phase of the project focused on the process validation of utilising Stereolithography as
a direct means to generate injection mould tooling inserts, which were fitted into an injection
mould designed for the trial purposes. The objective was to obtain process information with
regard to insert generation for Stereolithography. A three dimensional model of the part was
generated with CAD and the associated mould was generated around the part. The insert
halves were processed and solid epoxy inserts were generated with the 3D Systems SLA500
Stereolithography machine. These inserts were post-finished and fitted to the injection mould .
Additional features were added to the inserts to test cooling and gating and wear resistance of
the cavity material.
The author attended the basic injection tool setting course of the Plastics Federation to enable
him to contribute more directly to this process. This also highlighted some of the design issues
to facilitate ease of production . Initial difficulties were experienced in finding optimal process
parameters.
A total of 70 parts were produced, with measurable insert degradation. During the author's
training at 3D Systems in the USA, he obtained additional insight in current methods of insert
modelling and insert generation. If these process problems could be overcome, it would be
possible to produce in excess of a 100 parts with one set of inserts, assuming a tolerance
specification of 0.2mm. The cost of producing the inserts was approximately 50% that of
conventional tooling fabrication . The time lapse between growing of the inserts and production
of parts was one week compared to 6 to 8 weeks tool manufacture time with conventional
methods. The second phase of the project focused on methods to enhance the cavity surface.
Electroplating of inserts and inserts generated from Aluminium filled epoxy were tested , to
investigate the effects that plating has on tool life, dimensional accuracy, temperature
distribution, and the cost implications for these subsequent process steps. Stereolithography
inserts were generated, taking into account the design considerations. Aluminium filled epoxy
inserts were subsequently cast from silicone moulds drawn off the Stereolithography master
patterns. Two sets of Stereolithography inserts were plated with 20 ~m of electrolytic nickel
plating. One set of aluminium filled epoxy inserts were plated with electrolytic copper followed
by electroless nickel. The mould sets were subjected to the same injection moulding trials using
Polypropylene.
The third phase of the project evaluated the use of Stereolithography investment casting
masters to produce tool steel inserts, through the QuickCast process. Porosity was evident, with
substantial machining required to fit the inserts. Not all the detail was retained during the
casting process. Thin rib features on the part were thus lost. Due to the porosity the cooling
was changed to copper tubes fitted into the rear of the tool and back-filled with aluminium
epoxy. As the Stereolithography patterns were not polished the metal inserts had to be hand
finished. This was a time consuming process and skill is required to obtain a good finish. A
cost comparison indicated that machining aluminium inserts would be more cost effective. The
tool manufacture time and eventual cost is not significantly less than conventional machining .
In fact, trials with aluminium High speed CNC machining proved to be more time, finish and cost
effective. This is discussed as part of the trial examples.
Wax injection into AIM tooling was investigated on behalf of a client, with good results . As
ceramic and polymer injection are very similar, apart from the ceramic being far more abrasive,
it is the author's opinion that AIM tooling would be applicable, taking into account that fewer
parts may be achieved.
The KelTool process was also investigated during the author's USA visit. The licensing fees
and additional equipment are extremely costly due to the Rand IDollar exchange rate. Issues
related to this process are documented in this report.
Clearly the deciding factors remain the quantity of parts required and the complexity of form.
Each manufacturing process has a certain level of risk involved. Accumulative risk not only sets
manufactured parts at risk but could jeopardise project time scales and iterations of a process
have significant impact on a project budget
National Educators' Workshop: Update 1989 Standard Experiments in Engineering Materials Science and Technology
Presented here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 89, held October 17 to 19, 1989 at the National Aeronautics and Space Administration, Hampton, Virginia. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community
Volume 72 - Issue 6 - March, 1961
https://scholar.rose-hulman.edu/technic/1053/thumbnail.jp
Physics around us: qualitative problems in physics
ΠΡΠ° ΠΊΠ½ΠΈΠ³Π° ΡΠΎΠ΄Π΅ΡΠΆΠΈΡ Π±ΠΎΠ»Π΅Π΅ 1500 ΠΏΡΠΎΠ±Π»Π΅ΠΌ Π² ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΡΠ°ΡΡΡΡ
ΡΠΈΠ·ΠΈΠΊΠΈ. ΠΠ½ΠΈ ΡΠ°Π·Π»ΠΈΡΠ°ΡΡΡΡ ΠΏΠΎ ΡΠ²ΠΎΠ΅ΠΉ ΡΠ»ΠΎΠΆΠ½ΠΎΡΡΠΈ ΠΈ ΠΏΡΠΎΡΡΠΈΡΠ°ΡΡΡΡ ΠΎΡ ΠΏΡΠΎΡΡΡΡ
Π΄ΠΎ ΠΎΡΠ΅Π½Ρ ΡΠ»ΠΎΠΆΠ½ΡΡ
, ΡΡΠ΅Π±ΡΡΡΠΈΡ
Π³Π»ΡΠ±ΠΎΠΊΠΈΡ
Π·Π½Π°Π½ΠΈΠΉ ΡΠΈΠ·ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ²Π»Π΅Π½ΠΈΠΉ. ΠΡΠΎΠ±Π»Π΅ΠΌΡ Π½ΠΎΡΡΡ Π³Π»Π°Π²Π½ΡΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠΌ ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠΉ Ρ
Π°ΡΠ°ΠΊΡΠ΅Ρ, ΠΏΠΎΡΡΠΈ Π²ΡΠ΅ ΠΈΠ· Π½ΠΈΡ
ΠΈΠΌΠ΅ΡΡ ΡΠ΅ΡΠ΅Π½ΠΈΡ, ΠΎΡΠ²Π΅ΡΡ ΠΈΠ»ΠΈ Π·Π°ΠΌΠ΅ΡΠΊΠΈ Π½Π° ΠΊΠΎΡΠΎΡΡΠ΅ ΠΌΠΎΠΆΠ½ΠΎ Π½Π°ΠΉΡΠΈ Π²ΠΎ Π²ΡΠΎΡΠΎΠΉ ΠΏΠΎΠ»ΠΎΠ²ΠΈΠ½Π΅ ΡΡΠΎΠΉ ΠΊΠ½ΠΈΠ³ΠΈ. ΠΡ ΠΌΠΎΠΆΠ΅ΠΌ ΡΠ΅ΠΊΠΎΠΌΠ΅Π½Π΄ΠΎΠ²Π°ΡΡ ΡΡΡ ΠΊΠ½ΠΈΠ³Ρ Π΄Π»Ρ Π²ΡΠΏΡΡΠΊΠ½ΠΈΠΊΠΎΠ², ΡΡΠΈΡΠ΅Π»Π΅ΠΉ ΠΈ ΠΏΡΠ΅ΠΏΠΎΠ΄Π°Π²Π°ΡΠ΅Π»Π΅ΠΉ ΡΡΠ΅Π΄Π½ΠΈΡ
ΡΠΊΠΎΠ» ΠΈ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠΎ
- β¦